I would second Dirk's comment. The servo in my 280 SL finally got to the point of repair or replace. I asked around and found a place in San Diego that could do the repair. They had not backlog and I could have had the unit back the next day! I opted to fit my schedule and got back to them the next week.
I even asked them to not paint the front of the unit to keep the original white paint marks and stickers in place.
Not cheap, $450, but it is the original unit, it fits, it works, and was a relatively easy job.
Make sure that you note the position of the eccentric bolt at the rear of the unit so you can put it back in at the same position.