Motor hums till reset swithch pops/just put a new pressure switch on today:does the same thing/motor turns freely and oil level is good/no wiring issues visible

Loss of oil pressure or faulty pressure switch knackered oil pump
Main thing don't run engine till you find out what caused the problem as the engine can tear its self apart if its a pump or flow problem

Sadly Hunter doesn't want people dismantling their stuff and replacing broken or burnt out pieces. They'd rather you buy a new one. If the motor has burned out which is possible a solution depending on how handy you are is simply hunt down a similar replacement and reconnect it.

Make sure the new motor has the exact same leads and connectors as the old one had as some Hunter fans have more than two leads. The model I have has four leads: a black, a white, a green and a red as my model has integrated lighting controls by passed by the motor.

I bought a simple blower motor with the same rating only two wires and with a bit of solder and wire I hooked up the motor and lights separately. The new motor is much faster than the older one so I had to add a tiny 1-way 500 watt dimmer switch to manually turn down the speed.

Check the capacitor or the centrifugal switch.

I need the diaphram in the On/Off pressure switch on a Black Bull- 4 Gal., 2 HP, 5.0 cfm @ 90 PSI 120 v /13.8 amp . Batch # 0911. These are the only # I can find

The start button is used simply to get the motor up to speed to where the main windings take over when the centrifugal switch shifts outward at full motor speed. You need to examine the motor for excessive lint and manually move the cent switch to see if it is stuck. You can lube it after cleaning up the motor.
Use this good stuff to safely lube your motor cent switch and cotton wells

Wiggle that switch when oiling so it will slide easy

See the hole I drilled? Lube that well up real good and work the motor by hand till it turns freely

These wells on each side feed the sleeve bearing with a layer of protection between the shaft and bearing. The oil drys out and makes the motor drag. It cannot get up to full speed and therefore you have to hold the start button down.
Work the motor by hand till it turns freely, work the centrifucal switch till it slides easy.
OR just buy another motor and install it.

If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

The oil light is not an indicator that the oil level is low, its is an indicator that your oil pressure is low.

A dirty oil filter will make your engine loose oil pressure.

Of course no oil in the motor will also cause no oil pressure.

If you have the correct oil level and a new oil filter, and your oil light is still on.

Check that your oil pressure switch/sensor is working.(your oil light wire will go to the switch/sensor).

If your oil level is fine and the oil filter is clean and the oil light switch/sensor is good and the oil light still comes on, that is a sign that your oil pump isn't working correctly, and would have to be taken apart to see why.

Check the simple and less expensive stuff first, hopefully it will be one of those

either oil pressure switch is defective, not connected or there was not enought oil put back into the motor.

the start windings are probly burnt. does it hum when it his cut in. i had one the same. u bleed it down to nothing and it would start but slow. once its up to speed the motor switch snaps and u go to the other set of wires in the motor. it will work good till it cuts out. like u said no back pressure at the head. but wont anyway. well if u try to start it its not long and the short pipe to the check valve builds up if u start from empty the check valve can open and let the air out while it slowly speeds up if this sounds like ur problem then u need a new motor i had one i took apart and the start windings, the thinker shorter ones, were stuck together because the clear insulation melted together. i spit them apart using a screwdriver and gooped them up with that liquid black tape. put it together and nothing. found out i broke one. so i twisted it together good and put it all together again and pluged it in. it still works today. it was just a temp fix but i figure untill it stops working again im not going to replace it.

check for a re-set button somewhere on the motor housing.

ARE THE POINTS BURNT IN THE PRESSURE SWITCH? DO YOU HAVE A LEVER ON THE SWITCH SET TO ON OR AUTO? IF YOU THINK ITS THE SWITCH JUST BYPASS IT AND TIE THE WIRES TOGETHER TO SEE IF IT RUNS. BEWARE YOU HAVE NO PRESSURE PROTECTION EXCEPT POP-OFF VALVE. MOST P.O.S. COMPRESSORS LIKE PORTER CABLE HAVE 3500 RPM MOTORS AND HAVE A THERMAL RELEIF BUTTON ON THEM. JUST PUSH TO RESET. MAKE SURE YOUR WIRNG OR DROPCORD IS LARGE ENOUGH GAUGE. SMALL GAUGE DROPCORDS KILL COMPRESSORS.