I got an HP 6205B bench power supply from eBay, so I can start breadboarding stuff. The left side’s output was constantly at 40V and didn’t respond to the pots. The service manual is pretty thorough and has a little section about what to do when that happens, and one of the suggestions is to check if A6 to A8 is open (or some other two connections with A prefix). These are two of the terminals on the back and there was no jumper between them. I jumped them and the left side was working. Ordering a jumper for it.
Then I cleaned the enclosure because it was really sticky. The panels that were easily removed I took to the bathroom and washed them in the tub with dishwashing soap and a toothbrush. The front panel and knobs I cleaned carefully with hot water, dishwashing soap, and q-tips. I also discovered that the bottom pots (for adjusting the voltage) are missing the toothed washer and nut. At the hardware store these measured 3/8″-24 (meaning the fit over a 3/8″-24 rod but loosely). In reality, they’re 3/8″-32. Ordering a few nuts and washers right now. Getting a few extra because they fit other pots and 1/4″ jacks, so they’ll be good to have around.