Electric roof on 99 E320

My electric roof started doing a funny thing. When you press the switch to open it,it only moves about an inch. You have to let go of the switch and press it again about five times until the roof is fully open. To
shut it you can hold the switch and it will close all the way. Has anyone had this problem. Is it the switch or maybe the motor?
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I have these thoughts .......
If it isnt the limit switch setting then possibly exciess friction causing resistance and shut down due to motor protection. The startup current on an electric motor is much higher than a running motor so usually you can jump over small "bumps" this way.
It would be possible to drop out the head lining and have a close look at the mechanism.
Any lubrication needs to be complatible with whatever is already there as well as needing a decent clean out.
You dont know how much dust is in the mechanism. I suppose the other thing could be that after a loss of battery power the limits of the sunroof reset themselves in some way. You didnt really say if it was sudden or gradual failure getting worse.
As for the motor ..... its only going to work harder and suffer more if the mechanism isnt performing well.
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Thanks I will try giving it a good cleaning and lube job. Mercedes lube but of course
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