So you have 24-36 VAC or VDC floating on the chassis of the scope?? If so then I would about bet that your wiring is screwed in the scope or somewhere in your electrical wiring for the house. You have got a floating ground and you may get zapped messing about with the scope any further. Unplug it and have a person qualified to perform the work on the scope or at least have it looked at. Also check the house wiring at the breaker box and make sure that all breakers have a ground wire going to the breaker panel ground buss bar. Like CK said, AC power is not to be messed with!! It kills! Just be careful messing with the scope from here on out. Just some food for thought. Like I said, at this point I would not keep messing with the scope and also I would have an AC service tech come and cheek all your house wiring to make sure it's all up to code. JMHO's.