Hello, first post on this forum!

My post is about repair of an ss amp. I'm not sure if this forum is intended for repair questions, so please let me know if it isn't.

A friend has a Perfomer 1000 that was in a bad state: a bad repair of power caps that had desoldered themselves at some time.
I thought I could do a better job and took the amp home.
In the mean time i have replaced the power amp transistors and the elco's and it played so I thought I had fixed it.

However after 2 minute of playing, the amp starts to motorboat no matter at what volume ( so it seems like a power amp or power supply issue). Also the power amp gets extremely hot, even when not playing loud.
I tried using cold spray on the active components to see if the defect was temperature related, but I couldn't find a component that reacted on the cold spray.

Any ideas where to look?
Anybody seen something similar before?