odd SNES problem with RF?

[recorderdude]

OK, so I just got my super nintendo from ebay, seller described as in good working condition. Hooked er up, plugged in all the cables, popped in goof troop, turned it on and it works like a dream. A bit later, I popped in the same game again, and turned it on, but the signal doesn't seem to be transferring. The system lost the signal when it got shook and disconnected before, but even steady it doesn't seem to be sending it now. I saw it work perfect a half hour ago so it's got to be working right. Power light still comes on and everything seems allright. What should I do?

EDIT: fooled with it some more and tried a different RF (no changes so my RF switch is OK) and found out it's just really sensitive somewhere. Noticed the power cord goes in kind of loosely too. It's either working perfectly or giving the bluescreen at any given time and seems to change that when it's moved at all physically (e.g. ejecting carts, pulling controllers, etc).

http://www.ifixit.com/Answers/View/2...cable+plugs+in

I think this might describe the problem. I tried the prong moving thing but don't know if it worked or not since I didn't see them get any closer and the situation didn't change. Is there any way to fix this without buying more parts? If not I'd think it best to send the damn thing back since it was specifically stated to be working correctly. The strange thing is that the power light never goes off while the system is turned on regardless of how it's working, though.