I have a spider III, 75 watt amp that worked fine about 2 years ago, when I had to stop playing for health reasons. I am now able to play again, and I pluged my amp in turned it on and it still lights up like a christmas tree. As soon as I plug my guitar in, there is a "screetching" sound that does not stop. The volumes have no effect on this sound. Tried different cables. Tried different guitars. Tried different electrical outlets. Unpluged the speaker and pluged into different speaker and same issue. (so it's not the speaker) Has anyone else run into this issue? Any idea what to do. I contacted support, who say it needs to go to a service center. first off that 3 hours away. If I mail it back for service, it will cost me as much to buy a new one. Any experiences like mine I would appreciate hearing from, or for that matter suggestions. Otherwise, the amp is going to be used by my son in his matchbox village as a very expensive streetlight unit. Thank everyone!