Old (vintage) Marshall Amp

Here we have an old Marshall combo. At a guess it’s probably from the early seventies but I’m guessing. It’s been in storage for at 10years and it worked when I put it there. I’m waiting de enough not to plug it in to test it as that could cause damage. Cyril Ryan the amp guru told me about a simple mod to these that turns them into a beast of an amp. I never got round to it and Cyril retired !! So I’m open to cash offers as I want it gone. Cash offers only