I hope this isn't a question that has been beaten to death before but this issue is of a first time nature to me. I would appreciate any help in troubleshooting this. I have an '85 Peavey Bandit 65 Solo Series. Over the last couple of days it has started making a noise that sounds like a guitar cord is plugged in and is being touched by your hand. It starts low and gets loud but the amp continues to output the guitar signal. A flip of the three way ground switch stops the noise instantly until sometime later it again starts making the noise. Flipping the three way ground switch back to its original position agains stops the noise. This goes back and forth at about 3-5 minute intervals. The amp seldom leaves the house. The last time I used it away from home was October 2013. The only incident I can tie to the issue is that I unplugged a Digitech RP155 a couple days prior to this staring. Any ideas on what is wrong with this old Bandit? It's been a good amp for a long time and I hate to replace it but if it would be more cost effecient to replace it with another Bandit it will be what I go with. Still, I'd like to save it. Thanks in advance for any and all help!