My 1984 190E has 220k on the OEM transmission.

It also had a leak, and wouldn't shift right.

I replaced the vacuum modulator on the transmission itself, along with a filter and fluid change. The leak was from the modulator itself, and when we pulled the pan, we found that the previous owner had removed the filter, and didnt replace it. I replaced the filter.

I've been driving the car for 4 years now, and it is shifting just fine.

Maybe this is your problem?

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.