Here's an interesting problem I had recently, during new construction. I'll give you the basics of the issue, and you can ask me questions about any other troubleshooting evidence you can think of. What would you check? What course would you take to find the problem? I'll answer your t/s questions, as if you are working on the equipment.

First, the job. 2500# car, 3 stop, direct bore hole jack, adjacent machine room. 25 hp, submersible hydro, Maxton valve. All new equipment, oil and tank as clean as a whistle. Motor was Direct coupled to a small Allweiler screw pump. Very standard stuff for the USA. No weird stuff that would trick you. As common as a Big Mac.

Imperial brand motor draws about ~350 amps when starting up, on each leg. It was a constant draw, not just the in-rush. Made a HUGE humming noise, like it was under a great load. Slightly worse when running backwards!

Full Load Amps data on motor tag says 68 amps, iirc. 230 vac 3 phase coming from the disconnect.

Using Seimens 75G solid state starter, set at various starting currents, like 350%, and 200%. Didn't change problem much at all. Tried CBA and ABC rotation setings.

Checked all motor wiring for proper identification, grounds, and check motor for forward rotation. There were no grounds, and all the T #s were correct. (T1 thru T6) Motor windings read very low like they should, and did not read to each other, nor ground.

Pump wasn't turning under power, but with the power off, I could reach into the tank, and just manage to grab the motor shaft with my fingertips, and easily turn the motor/pump by hand. Should I stop now? Have I aroused some interest in this little troubleshooting example? Anybody wanna play my silly game? :^)