Thanks all! It WAS the capacitor. I got one from Grainger for $22 (ouch!) and it did the trick. I did learn about how those caps have a protection device that swells the top and rips lose the internal connections. Cool! Now I'll wait for a warmer day to check the charge. I was pleasantly surprised to find a boatload of paperwork including charts, part lists and instructions when I opened up the unit. I've been reading up on the unit and how to maximize efficiency with the proper charge. Apparently it was a very good one in it's day.
I also pulled the contactor and gave it a once over and dressed the contacts slightly but they were in great shape. The contactor seems to be another major failure point for this unit according to people on the web. No moisture ever got into the electrical area and the rest of the unit is sparkling clean. I hope I get a few more years out of it.