Right about the WD40 most likely mis-leading. (most likely a pecan hung up.
I've got couple similar to your rig that is old also.
Just some hints and suggestions:
You need to check the tank drain. May have water inside the tank.
Change the oil on the compressor and do not overfill. I use O'reillys 30w ND (non detergent) in my small compressors.
I put screen wire over the ends of the electric motor on mine to keep out dirt daubers.
If your is a v belt, (instead of a flat surpentine) if you don't know the size you can take a cloth tape measure and go around the OD of the belt to get the length. I use Kevar belts on mine with really good results.
Sounds like yours is probably wired for 120v use and the power strip won't be user friendly for the compressor. I wire mine for 220v, but mine are used stationery. Keep in mind that whatever the motor nameplate FLA or running amps listed, the motor draws briefly approx 6 times that much when starting so most 120v have to be on a 20 amp breaker and a short electrical cord when wired for 120v. (due to high staRTing amps)
Yep, those type compressors were built to last awhile with just little bit of TLC.
Eventually check the compressors intake air filters also.
You might find a parts lists for just the air compressor PUMP if you can ID it's model.
Some were made by Sanborn.
Be careful with that plastic knob air regulator, if you crank it in too hard the shaft will strip. (that regulator is kinda wimpy) I leave my regulator that looks like that one stationery and use a external regulator.
ALWAYS unplug the cord when working on th
e rig and always re-install the belt guard. They can take off big meat really fast and easy.
Next thing also that some forget. (or don't realize) If the compressor is in the middle of a pump cycle and electric power fails, they do not unload,
when elec is re-stored and it tries to start it will trip the breaker or smoke the motor if the motor is not strong enough to start under load.