A few people online have said that the Fender Bassman 100T Head has bias issues. They say that their tubes are damaged when they really are not damaged. I am wondering if the amp stops to play completely when it happens. I rather by a head than a combo Bassman.

Here is one review that talks about the issue:

"After using the amp for 2 weeks the auto-biasing system told me one of the tubes had failed. Strange, but possible. I spent $120 and replaced all the tubes for good measure. Same issue when I powered up. Come to find out via some online forums that this is a common problem with these amps. Not good. Fender was no help at all. They said, "sorry, take it to your nearest authorized repair center". I called 3 repair centers up to 100 miles away and none of them could help me. What a pain. I ended up sending it back to Amazon and getting a refund. I bought the equivalent amp from Ampeg and have had no problems. Fender really dropped the ball on this one. Maybe there are a few of these out there that actually work the way they should. But for $1400 its a huge gamble."
A false positive will usually just mean that the "tube fault" light comes on. It's not impossible for the amp to stop working with good tubes, but that is less likely and doesn't appear to be the issue discussed here.
Thanks, Roc8995!