With the aid of this great forum my mechanic has gotten my 1991 420 SEL with a rebuilt 560 motor running great. My next problem is that my transmission (rebuilt) flares slightly on the 2-3 and 3-4 shifts at partial throttle. At full throttle shifts are crisp with no flare. David Poole informed me that the 420 trans has only 4 clutches while the 560 trans has 5 so I'm assuming that this is a factor. I was hoping to have my mechanic adjust the modulator to alleviate the flaring but he seems to be having a hard time turning it. Is there a special tool? I never read of anyone else having a problem turning it.

Also the car will not kickdown at all. No part throttle kickdown and no full throttle kickdown. Any ideas?

The 420 and the 560 both use the 722.3 transmission which have 3 clutch packs, K1, K2 and for reverse B3. They also have two brake bands B1 & B2. The modulator can easily be adjusted without gauges if you increase it clockwise a little at a time. I would start out with one full turn and then test drive it. The kickdown issue is something totally different than modulator pressure. Check your control cable adjustment and then the electric kickdown switch under the accellerator pedal.

Thanks for your response. The issue seems to be that the modulator is difficult to reach and he can't turn it. Is there a special tool to grip it at an angle and turn it?