Which i ve never seen done on any compressor tank.
Compressor drain valve leaking.
Product links below in order of appearance.
Http amzn to 2ir0elq pittsburgh forge 12 piece screw extractor.
They usually use a high strength thread locker on the drain valves so it may just be very very hard to remove.
I would recommend replacing the valve and using some thread locker when you install the new one.
After cleaning replace the parts.
The valve on the outside of the pressure switch may look something like the one in the image.
To fix the air leak caused by a faulty drain valve there are three choices.
By the way c clip ring shown in the picture prevents the screw from being removed from the drain valve assembly.
If the check valve is now.
Drain the air tank from the drain valve.
Turn off and unplug the air compressor.
1 unplug the compressor 2 drain all the air from the tank 3 remove the lines connected to the tank check valve 4 remove the tank check valve inspect clean re install the same one or install a new one 5 reassemble and test the compressor operation.
Clean the regulator body air piston spring and cap with wd40.
Makita mac700 air compressor.
Besides the drain valve is relatively easy and inexpensive to fix.
Clean the regulator 4.
Remove the regulator body from the manifold with a wrench.