MB 300SD CCU vacuum solenoids too hot

[SilverStar011]

1984 Mercedes 300SD, W126.

Problem: The CCU six vacuum solenoids that control which vacuum pods receive vacuum are getting too hot (fire hazard hot).
Question 1: How many volts are supposed to go to the six vacuum solenoids?
(CCU vacuum solenoids a.k.a. 'gang of six' located near passenger left knee)

Test results: A steady 12V applied to the vacuum solenoid(s) overheats them (that's what is happening now). A bench test showed a steady 6V operates but does not overheat the solenoids.

It appears that a steady voltage to the solenoids is needed to stay open allowing constant vacuum to the pod(s). As soon as power to the vacuum solenoids is ceased, the pod(s) drain back of vacuum.
Question 2: Is the CCU supposed to step down the voltage so the vacuum solenoids get an initial 12 volts, then a sustained lesser voltage? If power is stepped down, where is that located.

CCU was reconditioned by an online service. CCU 126 830 0285.
Vacuum pods checked and do not leak. One side of the two part vacuum pod for external air flap (behind glove box) is plugged.
Blower motor speeds functioning correctly. Same results with two other blower motor modules.
Monovalve and Radiator Auxiliary Pump currently disconnected.

Thank you!