For starters, check out the DO IT YOURSELF section at this site. There are some good photos of brakes pad replacement on another model, but what you see there looks very much like what you'll see on your 126.
As for caliper/rotor removal, see the following thread:
Replacing front rotors on a 91 420 SEL
Wheel bearing adjustment technique is provided in this thread. BenzMac also suggests ZERO PRELOAD and ZERO FREEPLAY.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
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