[Amps] How to clean tube fins

[MARK KEMPISTY]

I'll be taking posession of an Alpha 78 in about a week.  One of the first things I would like to do is check and clean the tube's fins.  What's the recommended way to do that?

I will also check for what mod's have been done.  I know it has 10m.  Unfortunately the owner has alzheimers and cannot convey any details to the person handling the equipment for them.
Take care,
Mark 
AA3K