Old used kiln in the garage - what do you check before the first firing?

I picked up a used Skutt a few years back with one of those Kiln Sitters on it, and I went low and slow for the first run. Empty kiln, slow ramp to somthing like cone 015, just to dry everything out and see if the elements even pulled evenly. Took a few hours but it cost me almost nothing and if an element was going to let go, better it happens at low temps than during a glaze firing. For the sitter itself, mine was fine after sitting in a barn for who knows how long, but the thing that matters is the cone. I'd do a test firing with witness cones placed where you can see them through the peephole, so you know what the sitter is actually doing versus what the little triangle says. If the sitter trips way early or way late, you adjust the guide a hair and try again. Those things are adjustable for a reason.

One thing I'd add to your multimeter plan: check the resistance reading against what's stamped on the element or listed in the manual if you can find it online. A reading way out of range tells you more than just 'it's not broken in two.' Weak elements will still fire, just slowly and unevenly. Cracks in the brick, honestly, small hairline ones in the lid or floor are common on old kilns and rarely a dealbreaker. Big chunks missing near the elements, that's when I'd think twice.

I'm on the other side of this one. I've run three secondhand kilns over the years and every one went straight to a full cone firing on the first go. My reasoning is that a low dry run tells you almost nothing about the parts that actually matter. Weak elements tend to fail when they're working hard, and the sitter proves nothing at low temps because the cone barely bends by the time a gentle run ends anyway. If the shut-off is going to misfire, you want to find out while you're standing there watching an empty kiln, not later with a load of work inside. When I got my old Cress from a church sale, the sitter had sat dormant for six years. I did an empty firing to cone 6 and stayed in the room the whole time. It tripped maybe 40 degrees late, which sounds scary untill you know the trick: I had a witness cone on a shelf, and it bent dead on. So the sitter was close enough and a small tweak on the sensing rod brought it in line. A baby run would have taught me nothing about wether the shut-off works when it counts. The warped-parts worry is fair but easy to check without firing. The cone should sit flat on the plaque and the rod should release smooth. If the trip feels gritty or hangs up, the tube assembly is cheap and simple to replace. One habit I'd add: jot down how long each segment takes on that first run, then compare it against the next firing to see if anything's drifting.

One thing I'd check before trusting that sitter at all is the cone itself. Old cones that have sat in a damp garage pick up moisture and they bend unpredictably, sometimes way off their rated bend point, so grab a fresh box of the right cone before you draw any conclusions about the mechanism. While you're in there, look at the pivot points and the little tube the cone rests against for corrosion or a sticky claw, since a sluggish trigger will skew everything. Also pop the bottom or side panel cover and look for mouse nests, because old kilns in garages are basicly rodent apartments.

Before any firing I'd give the electrical side a once over. Cord, plug, and the connections where the element wires land on the terminals. My last used kiln had a element lead that had cooked the insulation back about an inch and a half from the stud, and that's the kind of thing a multimeter on the elements won't catch. If you've got a clamp meter, fire it and compare the draw to the nameplate, that tells you what the whole circuit is really doing.

Also plan for the first burn-off to stink. Old kilns that sat unused will smoke off wax and who knows what, so run it somewhere with airflow or you'll know about it.

Whatever run you do first, plan on it stinking up the place. My last rescue kiln put out this nasty burnt smell for the better part of an hour on the first heat up, old dust and whatever was soaked in the brick cooking off. I had it in the garage with the big door cracked and it still got into the house. Also prop an eye on it the whole first run, don't wander off, that's when things go sideways. Mine had one element sagging out of its groove near the top, just pushed it back in place cold and never had trouble after.

Total beginner here so take this with a grain of salt, I mostly mess around with a little heat treat oven for knife blades, nothing like a proper kiln. One thing that helped me with mine was finding the model number on the data plate and tracking down the old manual online as a PDF. Mine had a wiring diagram and the original element specs in it, which made the multimeter readings way less of a guessing game. Do older kilns like yours ussually still have that plate readable, or does it flake off after a decade in a garage? Also curious if anyone here has actually swapped elements on one of these, or is that a sign to walk away from a used find.