CompuServe Messages

I'm having a problem with the video hardware on my Amiga 2000 and I'm wondering if anyone out there can give me a hand. When my 1084S monitor is plugged directly into the machine everything looks fine, but recently I started having a problem trying to use a Digital Creations Super Gen. The image on both the 1084S and the video output from the Super Gen is unusable. It looks like a tv set with the horizontal control out of whack, lots of white diagonal lines on a black background. I had the Super Gen checked out and it is okay, it works fine with another 2000, and a different SuperGen has the same problem on my machine. The output from the Monochrome Video port on the 2000 is fine, and as I said the monitor connected directly to the 2000 is okay, so I assume there is a problem somewhere on my motherboard. So I have a couple of questions: 1.) Does this sound familiar to anyone? Any suggestions as to what may be wrong, and how I might fix it. I've opened the box up, checked the connections and the seating of all chips. Nothing appears to be broken. 2.) If I need to replace the motherboard, can I get one from somewhere, preferably as a swap for a reasonable price, are there places that deal in Amiga parts, and if so how can I reach them? 3.) Does anyone know of any service places in the Boston area that might be able to help me out? All the dealers and service places that I knew of seemed to be out of business. Any thoughts or suggestions would be greatly appreciated. Dave Roh