I read several posts on this board about the very same cruise control problems I was experiencing. I pulled and sent my amp and actuator to GDL for analysis after performing the tests listed on their site, and talking to Peter a few times on the phone. My amp tested poorly (as expected) but actuator tested OK (as expected). I had them open up, inspect, and clean the actuator anyway since it was already there and I didn't want to risk my rebuilt amp to a faulty actuator. Within two days of receipt, both units were back to 100% and on their way back to me. Install planned for tomorrow; will post results in this thread. Total cost about $300 including all the shipping.

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1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick