Disclaimer: Please read the user manual for safety information and understand this information worked for me but is provided with no warranty. If you're unsure then please contact Ridgid customer support or a professional repair shop.
Anytime I would use the Ridgid® OF50150TS MobilAir Tri-Stack™ 5 Gallon air compressor for more than a minute, like to blow dust off of vacuum filters, the compressor would stop and require manually resetting everything.
The problem turned out to be a bad check valve. This is a reasonably inexpensive ($15) and easy fix. It takes about an hour to remove the check value and install a new one.
It would do a few cycles of turning on and refilling normally. After the third or forth refill it would turn on and start refilling but then trip the small, round, black overload reset switch on the rear of the motor. When this happened it would stop running and you'd hear and feel a release of air from under the pressure switch (the black box with the red power switch).
Then, the only way to get it working again would be to turn the pressure switch off, release all the air from the tanks, press the black reset switch and turn it back on. It would run again for a minute and the same thing would happen.
I tried connecting the compressor to an outlet that is directly below the breaker box to ensure it wasn't wiring related. Nothing in the home breaker box or GFCI trips, so it wasn't a power issue.
The OEM part number for the check value is 079027013734. The internet suggests the old/obsolete part #'s for it are: 79027013712 and 079027013712
The check value is a brass piece located on the top-right front side below the red power switch. It screws into the upper tank and has one large copper line and a small copper line that goes under the power/pressure switch.
Be sure to empty any pressure from the tank and disconnect the power. Read the manual for other safety considerations.
Disconnect the compression fittings, unscrew the old part from the tank and then do the reverse to install the replacement part.
Be careful not to bend or break any of the copper lines or connections. Also, ensure nothing falls inside the tank. Wrap the part that screws into the tank with teflon tape. The compression fittings do not need teflon.
In my case the part I bought had a slightly different angle on the small compression fitting, so it was necessary to gently bend the small copper line to match up without crimping or breaking the line.