With the 16V air flow housing it is next to impossible to do any thing with the potentiometer UNLESS you remove the complete housing. After doing that 5-6 times at 2+ hours each, you can tend to get weary & just give up.
I did it on my 1986 190E 2.5 16V just 2 weekends ago in 2 tries, about 3.5 hrs.
MB # 000-074-23-14 is $755!!! so time can be your friend.
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)