Sticky shutter in Rolleiflex 75mm 1:3.5

The slow gear was very sticky in this old Rolleiflex 75mm 1:3.5.
I drop the very little screw that lock the retaining ring on the floor, I simply could'nt find that small screw again :-(.
After I made the film I simply put a small drop of nail polish to lock the retaining ring, it work's perfect :-)
In this film I use Isopropylalcohol to cleaning the slow gear, but I could also use Lighter Fluid, and to lubricate the slow gear I use sewing machine oil but ONLY on the axle end.