hopin it can be fixed.

I was just givin a an Industial Air air compressor. It's a reciprocating piston single stage compressor. Since it's still located in my buddys shop and accessibility too man. plate containing model info, hp size etc. is not possible at this point I'm not sure of that info. Here's the catch....the compressor is "locked up". Hence ...the reason it was givin too me. I'm a machinist by trade and I consider myself very mechanically inclined. I'm fairly confident I can restore it too working order provided I can locate replacement parts for the ones I may find defective. My questions.....Is this particular manufacture ...or whoever manufactures "Industrial Air" compressors still in business and how's the availability of replacement parts. @nd...Could you point me in the directions of possible reasons this compressor may be locked up? I'm very familiar with piston driven motors and engines but have no experience in this application. Thankyou for any and all advise you may be able too give me.