[morzh]

I have both 70 and 90 having zones where it is slipping. Guess it is quite a common problem for this type mechanism. I found out that moving the dial just a little along the axis helps it but you have to make sure it does not rub against the escutcheon.

Another thing, the grease tends to accumulate there and makes for less friction, so those need to be degrease.

Honestly, I do not remember this spring-pulled washer in either my 70 or 90. I wonder if they added that (or it was a home repair remedy) to increase the pressure of that rim onto that groove. I am not sure it is a factory solution - hadn't seen it before.