I have had a Crown Xti-2000 for a few years now that i I use on a limited basis. The last several times I have used it it either produces no sound from channel 1 to begin with or has channel 1 drop out at some point during the performace (mobile DJ work). If channel 1 starts out with no sound, it is usually able to be recovered by boosting the volume up all the way on the channel. It seems to me to be a possible short. I have tested this out with two other systems and I believe I have narrowed the problem down to the amp itself. Any ideas on how I can fix this myself or does it need to be repaired?