thumping

Hi All - I'm new to the group and just got (for free) a Velodyne ULD-15 Subwoofer Series II that has no foam. It was posted (from the daughter of the original owner) a properly working when put into storage 4 years ago and other than the foam looks in mint condition (beautiful cabinet and amp...

Alright so ive got a real stumper here. I purchased a pilot 240 integrated tube amp a couple of years ago from a kid on clist who had been using it as a bass guitar amp. When i got it one of the powertubes was redplating and there would be a crazy thumping, motorboat sound. This was my first...