Man" you really got some good stuff"" clean it off and check all the fluids first" try to find the filter and take it apart to if any waters in their.Man if ya get it function right that thing is better then any crap you can buy on here.If you could a timmer that works or own's a dive shop take it to him"You are so lucky""
Have seen and used similar compressors in dive operations in the Bahamas and Caribbean. They are simple in design and can
work if properly maintained. BUT, they need to be purged of moisture about every ten or fifteen minutes of operation. Some have two purge valves for different parts of the system. This is essential for clean, dry breathing or pcp air.
Looks like an old Cornelius with K valve fill. Great compressors. I have a couple and both work great and still pump to 3000 PSI.
I bought a 4500 PSI compressor so don't use them much anymore.
Most prople run Mobil Jet Oil II in them, I get mine off eBay. Jim Sheldon knows about everything there is to know about them and still had some spare parts a while back.