Hi. I'm looking into buying a broken V4; the price is too cheap to pass up. Anyways, the story goes that the owner replaced one of the 7027 tubes with a 6L6. An hour into playing, the amp broke down. Now it doesn't even turn on. Can switching in a 6L6 cause this to happen? I know that some variants of 6L6 can be used as a substitute, but to the best of my knowledge, the 6L6 isn't one of those variants. Please Help!