I have a Gaggeneau GM915-710 dishwasher, similar to many Bosch dishwashers with common parts.

The bottom spray arm turns slowly with only low pressure spray and the top arm doesn't spin at all with water just dribbling out.

I have done the following:
1. Cleaned out both top & bottom spray arms and the supply riser -- No blockages
2. Cleaned out the sump area -- No blockages
3. REPLACED the impeller and rear pump housing as they seemed worn (also removed some foil that was stuck in the impeller)
4. Tested the motor - at least to the extent that it turns - and added some grease to the bearings

I thought #3 would resolve everything, but nothing changed and the spray pressure is still very low.

Can't figure out what could be wrong?

Is it possible that the motor is working but "weak"? Could one or more of the windings be burnt out?
If so, how do I confirm that before ordering this expensive replacement part?

What else could be causing low spray pressure?