This is supposed to work as a "clutch" , it should be able to slip under extreme pressure.
At dealer we set up the clutch by allowing the motor to draw approx 10AMP(max) when at full open position. AT that point the clutch will slip. This is done with 17mm jam nut & large screwdriver.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator