I do not know if this is the case with the MB set up -- but you have antilock brakes -- it was my under standing that you should not push the calipers back in -- I use a "C" clamp also" unless the bleader is open.

The reason for this is to not push fluid/ dirt the wrong way through the antilock valves -- I know for a fact a few manufactures have this procedure.

I just open the bleeder and attach a hose anyway so my procedure is to always bleed the brakes anyway.

Also the pads and rotors for that model are not very $$ at the dealer -- much cheaper than most cars!