Musician 400 getting hot, shuts off after two minutes

[blazingsnowman]

Hello there. I have a Musician 400 I’m trying to revive. It’s been sitting at our band space for years. Turned it on and it works and makes sound for a few minutes then shuts off. The back panel and 8 transistors? are getting really hot. I took all 8 out, cleaned them, pinched their connections for a better contact, put it all back together and the same thing. Works for a few minutes then gets hot and shuts off. Any ideas?