I have never heard one of the kickdown solenoids. I have tested them electrically and never really heard anything. If the solenoid can be heard then I imagine it is working. All the problems I have seen with the o-rings are internal leaks which cause delayed upshifts rather than the opposite.

I would take a big look at the control pressure cable. I would probably make a huge adjustment to it and see what happens. By big I mean a quarter inch or so. make the cable shorter or the housing longer. (I don't remember how the adjustment goes on the 3spd Porsche application.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician