"Pro" is the later head version I think. The SVT your purchasing is the '90s rack version with the EQ on the front, yes? IMHO, the best bass amp of all time, it will eat other amps for breakfast. Its not good for jazz or worship, but for rock and metal it will pound all other amps into the dirt.
Take it to a good technician. It's worth fixing.I just picked on up for $500, guy also has an SVT4 for same, wondering if I should grab it?
Amp sounded beautiful for about 10 mins before losing gain and gaining static, did it 2x. Sad, but might get the 4 for even less.
This amp burnt 6550s in the past - anywhere else I should look for issues? Sockets all fine.