Sir art blank . . . . . . .
But . . .BUT . . .BUT . . .BUT . . .that thing is getting old and feeble and you shouldn't expect it to be on duty 24/7 for your beck and call for opening its door for you ! . . . . . after all . . . . .and that's being spelled with a HEAVY . . . .
A l l l l l l l l l . . . . .of these years.
One normally expects to find an el cheapo mechanically latched and spring loaded door used for that function.
On your unit with the "soft touch " . . . your pressing against a "tact" switch, should then engage its electronics to activate a motor driven geared ? belted ? performance of those open / close functions.
Now on your part, you are going to have to crack some eggs to make that omelet . . . . . .
(PULL the units top dust cover .)
Fortunately many years back, I had a second nephew , twice removed, that had one of those units in a complete Technics stacked set up and he got its service manual and had me repair it for him . . . .however,it was having a no sound problem.
With your MOST informative info, already presented, with it affecting BOTH decks, we can rule out just about everything but a power supply or interconnectivity problem COMMON to both units..
It looks like the unit might rely upon a constantly running reel drive motor that ALSO intermittently mechanically kicks in and supplies the mechanical drive for the door mechanism by the activation of an associated solenoid.
Limit switches L 801-2-3-4 tell it when to start or end its mechanical engagement.
I will initially send you this "snippet" , placed just below, of just the first preliminary checks, to do.
If you will send me a one of this forums "conversational" messages with your Email addee, I can then send you the units whole service manual and schemas . . . a la . . . Pee Dee Eff.
Now . . . .what'cha . . .gonna find ?
REFERENCING:
73's de Edd