First, can we all stop saying we 'won' something on eBay? We were willing to pay more money for an item than anyone else, period.
Second, you bought a broken amp. Unless the seller described the item as as-is you should seek a refund, because there are plenty of B-25s in working order to be had.
That said, Jess Oliver's company had a reputation as the premier bass amp company back then, so I doubt he would have allowed poor designs to hit production. Check the solder joints carefully.
As Keith said, the second thing you should do is try swapping out the tubes for units you are confident are in working order, but only if they are correctly biased and sold as a set. Mis-matched tubes can cause damage, I'm told.
I would hunt for tubes at radio and electronics trade shows...a number of years ago, my Dad, a radio fiend, found a set of NOS tubes for an Ampeg M-15 I then owned at a computer show for a few bucks. That set included several highly obscure tubes, items that usually trade at high price.
Good luck.
