It's a single phase motor with capacitor odds are its something wrong with the centrifugal starter winding switch gear inside or a wiring connection issue with the capacitor. If its fairly new the capacitor should be fine but sometime you do get infant mortality where one just dies at not very old.

Test is to get the spindle spinning and see if it picks up and goes when you hit start.

Sometimes its a contactor coil issue. Taking current but not enough to operate it. Not unknown when someone has done a three phase to single phase conversion on an old machine without noticing the contactor coil is 440 volts. Which shouldn't apply here unless someone has changed the contactor without checking coil voltages. I have seen one where the innards weren't lined up and there was enough mechanical ressistance to top the contactor working. Not quite tight enough screws let things shift over the years.

Clive

Edited By Clive Foster on 09/12/2022 12:45:47

Hi Jon

Whoever tasked you to repair the drill must have some confidence in your ability to effect a repair so I find it strange you would need to ask such a question, unless of course you are just seeking confirmation of your diagnosis.

As said by others check the capacitor if fitted and the centrifugal switch for correct connections and operation.

Emgee

As it hums, twisting the chuck by hand might start it. If so the capacitor hiding under the motor plate sticker is usually dead.