2003 350SL Central Locking Problems

[Mantaraman]

This is a a plea for help sorting out the central locking.
The car doors will unlock when requested by the key fob and dashboard button. Air flows through the vacuum pump - exits via the small exhaust "filter".
The doors will not lock, either by fob or button. The vacuum pump runs. No air through the pump/"filter".
The boot lid will not lock or unlock either by fob or driver's door button. Vacuum pump runs - no air flow.
The boot lid soft close pull-down doesn't work. The pump runs - no air flow.
I've dismantled the pump and checked the rotor and vanes and they are fine. It will pull 4 bars vacuum.
I haven't done anything to the car (remove door cards, boot trim) that might have damaged any of the vacuum pipes.
The boot lid lock/pull-down mechanism seem to be in good shape, no vacuum leak but, as said above, no air flow through the pump.
I wonder if there is a re-set procedure?
I've looked at lots of posts and videos and haven't come across these symptoms.
Any help would be much appreciated.

 

[ABZSL55]

following as having similar issues with soft close although locks all work fine.