Hello, I have a Crate BT220 and I have problems with the speaker. Once I turn on the combo and begin to play the speaker works but after a couple of seconds it goes out. The headphone input also stops working when the speaker stops working. I tried to plug the bass into the other inputs but none of that worked. I also tried to bridge the effect input and output to try and see if that worked but nothing. This is my only amp and I would really like to repair it. Tuner works Most of the pots are scratchy Any suggestions?