Hello, I've searched for this, and haven't quite found the information I'm looking for yet. Maybe some people here can help. I have a '66 Bassman head that was acting up, and upon taking it to a tech, I found out it had a replacement output transformer in it that was not the correct replacement for this amp, which was causing the amp to run improperly, and needs to be replaced. My question is, which company and which model transformer is ideal? I've read lots of back and forth debate over whether or not it's worth it to spend extra money on Mercury Magnetics transformers, and I don't know what to believe. Can anybody steer me in the right direction so I can get this amp back in playing condition again? Thanks for any and all help, I appreciate it! Cheers!