Old school RF PA-1 Pre-Amp question?

[SWGAaudio]

So I recently found my dads old school titanium Rockford Fosgate PA-1 Pre-Amp. I cleaned it up and it seems to be in good shape! My dad said that he does still have the titanium knobs I just have to find them. My question is do you think it is still usable? It wasn't in the best storage (grandparents garage) but I don't think it will be scratchy. And if it is, does anyone have any information on how to clean one and make it work like new? I really want this thing to work since it's kind of hard to find the titanium version of the PA-1, so any information is appreciated.

http://postimg.org/image/h7aqpj34p/