That compressor is entirely rebuildable. It's a Saylor-Beal design. You'll find the parts online. I think I'd pull the head and replace the reed valve assembly or at least clean the carbon off the reed valves and head and install a new head gasket. It's after cooled, a good thing. Change to oil too. I';d say t's probably 30 weight non detergent but there are reciprocating compressor specific oils on the market, I use Rarus (Mobil) reciprocating compressor oil in all 3 of mine, yes, I have 3 plus an IR inline refrigerated air dryer. I use lots of air when pressure sandblasting and running my plasma CNC table. All 3 of mine running together gives me 30 CFM at 135 psi. In reality to run anything, 135 psi is plenty (including impact tools). The lower the cut off pressure is, the less wear and tear there is on the compressor and less carbon buildup on the reed valves too.
Clean and/or replace the air filter as well. I replaced the air filters on mine with K&N cleanable air filters, it's a Solberg air filter btw.
My Champ has a 120 gallon vertical receiver (tank) and a 7.5 horse capacitor start, induction run US motor. The other 2 have 5 horse cap start induction run motors. Looks to me like yours is a 5 horse. Keep in mind that with any cap start motor, inrush amperage is 3 times running amperage, so if the motor is pulling 10 amps on 220/1 running, it will take 30 amps to start it. Easy enough to ascertain running amps with a clamp meter.
The unloader is very important as the compressor needs to have the head unloaded to start correctly. The unloader on a Champ works off the end of the crankshaft with a poppet valve in the head.
Mine is at least 30 years old (bought it used, in fact bought all 3 used), rebuilt all of them and the all run just fine and are hard plumbed into my air system in the shop. I have it set up where I can run just one if I don't need a lot of CFM, or I can kick in another or all 3 if my air requirements cll for maximum CFM.
Reciprocating compressors never wear out (so long as you change the oil regularly and keep the reed valves carbon free. The killer of any compressor is water (condensate) in the receiver. All 3 of mine have automatic tank drains installed. HF sells a nifty and cheap auto drain setup that works off the unloader poppet. 2 of mine have the HF auto drains and the 3rd one has a 110 volt timed drain.
If I get time, I'll take some pictures and post them.
