Mono on mine was much quieter
I really liked the quiet mono wiper on my old 87 300E. I have traded up to a 95 S420 and it has standard 2 wiper system which makes much more noise and even with new blades installed does not do any better job than old mono system on 124 car. Keep new refills of OEM ? (bosch?) and check post for lubing of the unit if it still does not do well. I miss mine!