I've just started having problems with my amp. It seems that after a few minutes of slapping...the volume gradually cuts out. At first I thought it might be the active circuit on my bass but when I bypass it, the problem is still there...But if i just tap the head of my amp it goes right back to normal volume...what could this be? I've only had the amp for 10 months and its new. And if something is wrong with it how can I get it fixed?