I would check two things first. First would be the large diaphram below the top cover. It is the device that lifts the piston as load is applied.
Second I would check the available voltage/ignition waveforms. Lack of available secondary voltage or a shorted coil wire/rotor can put the thing out like a light. As I have stated before all these things as testable. All you need is someone who knows how it works and the tools necessary (which might include an exhaust gas analyzer in this case).
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician