[ccomer1955]

According to a visual inspection of the scope, the green ground wire is taped up and secured to the side of the power transformer without making contact with anything. According to the schematic, there is no green ground wire at all, correct? It looks to me like the transformer grounds to the chassis? Ground appears on the schematic as coming out of the transformer on the side.

But...why would this scope have a three-prong cord at all if it makes no use of the green wire?

Little change when I short the leads.

I cleaned the pots and switches and saw no real improvement, either. I also gently moved a few wires that were making contact with parts of the sweep switch. Nothing.

It looks like one of the grounds isn't making good contact, then? I guess I'll start tracking them down.