when going down any kind of decline or slope in cruise control, my 560SL surges (power on/power off). The cruise seems to operate fine on an incline, but seems slightly unsteady on the flat.

Is this a self-fixable item? (and if so, any hints or cautions?)

Check the throttle linkage for ease of movement. Also check the throttle plate (the rod that goes straight down near the front of the air flow sesor plate housing). These cars can get enough crud around the throttle plate to make the plate stick. When the cruise goes from closed throttle to open throttle, it has to overcome this resistance to movement. Then when the throttle "snaps" open, its open too far...so the cruise backs off causing a surge.

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W.R.Durrance
ASE Master Tech
Mercedes Tech 19 Years

If this doesn't cure it, I have seen many control units fail. You can get a rebuilt one from us.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks to both of you...one follow-up:
What would be the most effective way to loosen and lubricate the linkage?

Use needle nose pliers to snap the balls sockets off. Then use a thin grease inside of them and reinstall.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

i hade something of the same problem except it pulsated when i turned the turn signals on
i finally found that the fuse was getting erroded away at the end r/r the fuse and now works fine

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KEITH