Of course I'm going to send the amp into a tech to check it out. I never said anything about saving a few bucks. I know how serious this is, that's why I've unplugged my amp and didn't bother touching it again while posting this question. I just want to find out if this is a common problem with these old amps, and isolate it so that I know what I'm dealing with before sending it in for repair instead of blindly taking it to the tech.
I probably won't be able to do this until the weekend though, so I'll just give you guys some more info to help isolate the matter. I've noticed that the mark had this very strange hum coming out of it, and if I touch the metal knobs on my guitar, it sounds scratchy like the pots are dirty or something. I thought it was the guitars fault at first, so I tested the guitar through other means (i.e. a POD and a practice amp). I confirmed it wasn't the guitars fault for the noise. Next, I really doubt it could be my houses wiring, but I won't know for certain I purchase an outlet tester. I've never had this hum problem with my old roadster in the same outlets I've used for my mark. I even plugged my amp into two different sockets in a different room (this is when I received a shock for the first time). I used both wall outlet and power bar (it's a pretty new power bar from a reliable brand, and not a cheapie you get from the dollar store).
Going from these facts, it's likely that it's the amps fault, and that is a grounding problem. I must add that I think that the ground switch might be defective, as it doesn't respond at all when set in any of the three positions.
So if anybody can let me know if this sounds like a familiar problem (i.e. defective ground switch), please let me know what the possible problems are, so I can take it to the take and let him know exactly what I think is going on. I'm obviously not going to be to playing around with the amp or testing it further until I get this problem fixed.
Thanks guys