Hi Mauro,
The felt type strips on the top of the doors are probably not your problem, however I would replace them as well.
The doors have adjustable guides front and back, which should be OK, meaning they most probably would not need adjustment. Marked in green.
The red ones are adjustable aluminium slides which is attached to the glass and the blue ones are nylon slide fittings.
Make sure you have these parts in the doors and in position. You would probably only need a set of the nylon slides. The aluminium ones do not ware out, but they might be missing.
I bought my 250Sl after a very bad 8 year restoration. When I opened the doors in order to adjust the side windows, I found most of the red and blue slides were missing.
Regards
Chris
Cape Town