Need help troubleshooting SONY CD changer

[kstinmb]

I need some assistance troubleshooting a Denon CD changer DCM-444 (not SONY, my mistake). It's a changer which uses standard 6-disk cartridges. I am waiting for a service manual and schematic to arrive.

The problem is that when a cartridge is inserted and it tries to inventory the six CD trays, the spindle never spins up. Each CD is properly extracted from the cartridge in turn, but they don't spin and aren't recognized.
With power off, I applied 3 volts to the motor and it spins right up to a constant speed, so it appears to be OK.
Where do I start looking?
Thx,

There are two short clips of the failing load here:
https://youtube.com/shorts/1QTUwAoi0bo?feature=share
https://youtube.com/shorts/bjNUy-BI_Tc?feature=share

 

[kstinmb]

Does the CD drive use the laser to check whether a CD has been loaded? Before it spins up? If not, there must be some other sensor which detects the CD and allows the inventory to proceed.
Has anyone successfully solved and fixed a non-rotating spindle motor?
Thx,