Quite a bit, actually. I bought the lathe without running it but with the expectation that if I couldn't get it working I could always flog the tooling on eBay for the purchase price, there was quite a bit of tooling and one bit would have covered the price in it's entirety.
On arrival the controls on the lathe were rusted, and the drive was not completely working. I started dealing with the rust by removing things and cleaning, most of the rust was in the zero setting dials and such and interfered with the tenths clearance. The taper vernier dial took most of a week to get apart - one hour at a time in solvent in the ultrasonic bath, but once it got open .002" the rust was able to come out and it was cleaned and back together in an hour or so. It was the worst, really.
The drive was a lot more work. The tubes (this is an all-tube drive) was OK, a couple of marginal signal tubes were replaced. I found a couple of caps that were marginal, repaired those. I had the motor armature turned and new bearings and brushes put in, they managed to mess up the series field (this is a compound wind motor with series and shunt fields) and that caused some fun until I stood over them with the motor on the test drive - it would arc like crazy after the field crossover point. Once that was fixed I had to replace on of the special rheostats in the speed control, they each vary only on half of the turn but on opposite halves and someone had put in a standard linear taper pot. That was fun as the drive was increasing the armature voltage the filed was decreasing. Anyway, that was about 3-4 months, and a niggling problem I caused during this time took a couple of months to track down (a whisker of the wire on the pot was touching the lead primer paint inside the pot housing, and was draining off *just enough* of the gate that I couldn't get the field all the way down...) but since fixed has not given a lick of trouble.
During that time I was doing "weekend projects" - take something off, clean/repair, replace. After a while I had a lathe with all the functionality but a very worn bed - .007" in the front inverted V. I finally bit the bullet and broke the lathe down into components. The bed, saddle, cross slide and taper slide all went with me to Dallas for a grind, I had the bed top ground, the saddle had the cross slide dovetails ground and top cleaned up, the cross slide top was squared up and the taper slide had the inside ways parallel ground.
When I decided to strip the lathe I also decided that a stripped lathe was a lot easier to paint, so from this point on I was removing old paint and priming/painting as necessary. I ended up painting the base, bed, headstock, gearbox, saddle, apron and tailstock in that order, pretty much as things went back on.
Realigning the headstock was interesting. I had to scrape the headstock back into alignment while maintaining bearing on the ways. I was lucky to get it in as few cycles as I did, I built a spreader bar that helped lift the headstock on and off the bed as well to flip it over for scraping. I scraped the tailstock base in to the bed to use as an indicator holder to check the headstock alignment, made it level to the leveled bed at the same time. I think I stopped when the 1.375" test bar was .0004 low at 18" - if I remember right that was the droop.
The saddle was a lot more work. I had to set it the proper height above the leadscrew and feed rod so that the apron would have the proper alignment, this entailed removing some material from the V ways and replacing it with a castable resin called Moglice. The minimum thickness of the resin is .032 thus the V way cleanup - it also removed most of the oil and such and put some tooth for the Moglice. The wear was considerable on the saddle, once I had the bottom the right height and the top level I used feelers to figure out the cuts - on the leading edge I only needed to take off .012 to get the .032 I needed. In casting I placed a couple of layers of tape on the bed ways and cast the oil grooves in place. I also had to replace all the oil lines in the saddle as they were gone (I'd patched over some rust areas that leaked, but this was the time to finally replace with copper. The meter units had been replaced some time before when they were found to be clogged.
The apron needed a lot of work. The bushings for the feed rod were egged out where the rod passed through, so I had to bore them out and put in some bronze replacements, keying them in place. Most of the bearings had to be replaced as well as the arms for the oil pump and the cam on the longitudinal feed that worked the oil pump (the pump has 2 cams, on for cross feed and one for longitudinal), the worm gear on the feed was about gone and had to be replaced, the pinion on the rack needed replacement. The oil pump was rebuilt, not really needing it but as long as I was in there....
After the saddle was Mogliced and some oil pockets scraped, the apron and all the associated rods put back on, and the electric leadscrew reverse put back on in time. Lots of finagling there. Since I had set the cross slide square to the headstock when doing the Moglice all I had to do on the cross slide was to mill the bottom for some Multifil (a way material like Turcite). I glued that up using a surface plate as a master so it'd come in flat, and it needed very little scraping. I needed to do the bottom of the cross slide before calculating the verticals, and after getting it to the right height I was able to shim the gib in with a .002 shim, and I've put off the final fitting. Maybe this summer.
The compound was scraped back in, the base milled flat (.005" wear - from rotation, believe it or not) and scraped to the top of the cross slide. I've since replaced the compound assembly but have not yet refitted it.
The tailstock was low and I simply shimmed it .006" up. It was level from scraping the base earlier. I had to make a new nut (1/2-8 LH ACME, so I had to make the tap as well) earlier and made a couple of new quill assemblies as well, one in MT2 and the other in MT3. The eccentric on the tailstock clamp was shot and needed a new one which was made,and a replacement handle I had for the clamp fitted (someone had bought one for the lathe but never fit it). I think they're riding in new bushings now too.
The taper attachment needed new bearings all around (8 of them) and I rebuilt it to fit the new slide. I still need to mill off the sides of the part that slides in the body to clear off some pitting, I plan to attach some steel strips and to grind it all parallel. It's "ok" right now if I simply avoid the last 3" of travel near the headstock, and with better than 10" travel that's fairly easy.
Most all the gaskets were replaced in the process. Someone had used some black goop instead of gaskets, and this was a mess to cleanup, entailing some serious work in the bottom of the gearbox. All wipers and felts were replaced. In general all oil passages were cleaned and verified to be working.
In retrospect it might have been better to get a lathe in better shape, but really, a lot of this sort of thing would have to be done anyway sooner or later. What I did was far from a 'concourse' rebuild, ignoring the paint (well, it's not the best in the world, but it's 'serviceable' and looks pretty good from 10' away). I was mighty tired of stripper, bondo and toluene (I had to shoot a lot of paint in 45 degF) by the time I was done.
I did do some 'bling' stuff - the beat up plates for threading/feed and controls were replaced with new where it didn't cost much. I tapped the old drive screw holes and used screws in replacement. But generally if a part was serviceable I simply cleaned and reused it. Since finiahing the rebuild I've replaced the cross feed screw & nut and rebuilt the dial assembly, and replaced the screw in the tailstock, both feel a lot better now.
Before and afters are here: