THANKS - answer found in the owners manual, of all places
I have a PS2 Railking F3 ABA set I just unpacked after many years and the rear power truck was frozen.
After applying lite and gear oil itʻs free but the swivel action is still too stiff to run.
The rear truck in the B unit (foreground) was also frozen but freed up nicely.
How do I remove the powered truck to remove what is binding the movement?