Studer A810 Tape Lifter Problem

[Billicar]

I have a Studer A810 on which the tape lifters do not work (in Fast Forward and Rewind the tape remains in contact with the heads).

The solenoid is fine, as is the Tape Deck Controller PCB.

I have swapped the front panel Command Unit with one from another A810 and then the lifters work fine, so it would appear to be a fault on the Command Unit.

Everything else works fine, however, on power-up not all of the lights on the Command Unit come-on (Programmable keys Y and Z do not light, although they work as they should after power-up).

Any help would be gratefully appreciated

BTW, I do have a service manual with schematics.