Compressor won't start up ...Ideas?

Gonna take a wild guess.............the capacitor is shot on your motor; it, the capacitor gives a little extra "kick" to start the motor turning, with out it the motor goes "locked rotor" . Might be able to get a replacement, it is located under the "bump" on the side of the motor, they are rated/sized in "micro Farads" (uF ) , with compressor unplugged, short across the terminals with a screw driver to ensure it is unloaded before unhooking it, you could get zapped if you don't..............OR, the brushes in the motor are worn out, might be able to get replacements........................ OR, junk it and buy a new compressor, it doesn't owe you a thing after 15 years