Then take the motor off and take it a place that refurbs or rewinds them. They can either repair or source a replacement. Motors are fairly universal things. They can also test if it works.

And just because it is in an industrial unit, means nothing.

I worked as a spark for around 15 years, and some of the things you see people using are unbelievable. Whether just shoddy work, or undersized cables, terminations, etc etc

Unless you have a minimum of 6mm^2 from the incoming Electric Board mains to the compressor connection point itself, then IMO it is not sufficient.

At the minute you still dont know why the unit doesnt work. Just that it doesnt work, and internal parts had been tampered with.