There is a big difference between the sun (or moon) roofs of a W124 and a W210. The older W124's have the motor for the roof in the trunk and the newer W210's have the motor above the courtesy lights.
As Ed already told: it is probably the switch and this can easily be checked by using another switch (if you know a relative or anyone with a same car and sunroof).
There is a possibility to fine tune the sunroof's motor in the trunk of a W124, but I don't think it will help you.
Try another switch...
with a minor 600+k