I've had four MB's over the past three years and all of them came to me with non-operational CC units. The first, a 240D just needed a rebuilt amp. The second, a 300SD, needed that plus an actuator. The last one, Strider, had a factory amp ($550!) installed a couple of years before I bought it. The CC didn't work in that one either, but since I knew I likely had a good amp, I tried a known good actuator. Problem fixed. But then I put the old actuator in my wife's car and it worked fine. Hmm. Then Strider's CC began to faintly surge. I poked around and the next day everything was OK again. The next week, the surge started again and got worse until it was surging +/- 5 mph. I use my cruise at least 2 hours a day and can't handle it not working for long.

This time, I removed the big actuator connector (located on the driver's side fender) and cleaned the pins and coated them with dielectric grease. The connector seemed a bit loose, so I used a couple of nylon wire ties to keep it firmly in the recepticle. That was a month ago and the CC has been perfect since. I think that sometimes the surging problem may be caused by a poor connection at the actuator, not necessarly a bad actuator or amp. It's worth a try!

__________________
1984 300Sd 210k

Former cars:
1984 300D 445k (!!) (Strider) Original (and not rebuilt) engine and transmission. Currently running on V80 ( 80% vegetable oil, 20% petroleum products). Actually not, taking a WVO break.
1993 300d 2.5 275k. Current 120/day commuter
1981 300SD 188k (Hans) Killed by a deer