Diagnosing bad motor/driver. Vibration at low speed

[threedee]

Hello people.

Finally started rebuilding my laser bit by bit, after getting fed up with sellers warranty fix promises.
Today is X axis stepper/driver's turn, as rebuilding X axis.

I'm having moving resonance issues in toolpath. Someone suggested to run a project and keep hand on the head as its moving (dont worry, laser tube was off :D ). I noticed pretty strong vibration in X direction while accellerating/decellerating and on constant low speed (10-30mms).

Before i had been advised to swap over drivers to see if other problem goes away or moves to other axis (X overheating with a lot of small acc/dec movement). It didnt. Drivers function.

Question is are they functioning correctly ? Or is the motor flaky ? Do stepper motors go flaky ? Not outright dead but weird, ghosts'n'stuff?

As for drive spec - no clue. M415DRV. Unidentifiable. Current set to 0.57A RMS. Stepping X32.
Motor is 17HA705Y-1A, FH171215 Smooth, 34mm nema17. Again, unidentifiable.

Any way to diagnose this without outright replacing motor and driver ? (which i dont have spares of).

#Edit# P.S. I cant seem to disconnect the "connector" on the motor. Is it just a piece of plastic and wires are just there ?

[routercnc]

I would expect that connector has a small hidden tab of plastic which needs to be pushed back by a thin screw driver before it can be removed.

Once removed you can try a multimeter across different pairs of terminal pins and check the resistance across the coils. On my motor (completely different Nema23) this was 8 ohms ? can't quite remember. If you look at the colour coding on the wires at the connector and trace them back to the stepper drive you can see A+ and A-, and B+ and B-. So there should be resistance across the motor pins which where connected to RED and BLUE (A+ and A-), and across WHITE and YELLOW (B+ and B-). Infinite resistance across anything A and anything B.
Since it works, but with some vibration I doubt the above is the issue.

If you can't remove the motor connector then remove the green terminal block from the stepper driver and put the multimeter probes in there as this is a direct read of the motor windings.

I don't know much (!) about small Nema 17 motors used for lightweight laser printers but the MS on my router is more like 800 or 1600 (it was a long time ago). At x32 MS (3200) sounds like the driver would be working pretty hard? Is there a manual which states it needs to have this setting? You could try changing the DIP switches to drop to 1600 MS. Be aware the laser will move the wrong distance but you may be able to jog it around at see if the roughness is improved. Then change the 'steps-per' configuration in the laser software (assuming this is configurable).