Yep, when I had issues with my lights not levelling - just shaking about for a 30 secs before lighting up the road for 5m - they thought it could be the stepper motors which move them up and down to level them. In my case both lights were doing this, so unlikely that they would both fail at once... Turned out - we think - to be the intravee I have fitted sending signals through the LCM that it didn't understand, as I have the sidelights set as DRLs on the software. Turned the function off, reset everything and they worked fine, though I couldn't use the function. Of course I updated the software, tried it again, and now they are misbehaving again...
If you have an intravee fitted it is worth switching any lighting functions off (DRLs, one touch indicator blinks etc.), select the radio rather than the intravee on the stereo, switch the car off and leave it for a while. The lights should work okay after that. Reason I say this in your case is because recently one of my lights was adjusting and the other wasn't... And now it's fine again :?
If you don't have an intravee then the stepper motor is one element of the light that is replaceable ; the other is the ballast, but I think that's the igniter rather than anything to do with levelling. Could be wrong though, so someone may correct me. It wouldn't be the levelling sensors on the suspension arms, as that would affect both lights.
Sorry for the essay
