I have a lot of Compur shutters that needs service. I have tested my skills on some Prontors with reasonable success but I suspect that the Compurs are even more demanding. So I figured it would be wise to start with an early version ...
A Voigtländer Avus 9x12 camera of mine has a Dial set Compur shutter. It ran at full speed on all settings. And I could see that one of the 3 blades was not sitting right. Plus, the aperture blades all looked fine but I could not adjust it the full span.
Getting inside I found the unit next to the main drive was cluttered with old stiff grease:
The stiff grease would not allow the lever that couples to the gears to return to its start position. In addition: the spring on that lever was rather slack. (It had no tension at all against the post when I pushed the lever to its start position.)
I removed, cleaned and very lightly lubed the connection from the main spring all the way to the pendulum with dry moly powder and carefully blew away what did not stick. The surface of the main drive I gave a little bit of new grease. Also the other long lever controlling the action of the pendulum on the star wheel was cleaned and very lightly lubed with moly powder.
This made the 1/1 setting run amazingly correct!
***
I left most of the other parts of the mechanism untouched as they seemed to be OK and went to visit the shutter blades.
Two of the blades were where they are supposed to be: seated well on their respective pins. But the third was supposed to be fastened by a screw. That screw had become loose. I found it in the channel for the aperture blade connection. I cleaned the blades and the plate and put the blades back.
The shutter is now running quite nicely. The three slowest speeds I'm actually tempted call perfect! But the faster speeds are all somewhat slow. I may get back in to clean the actuator ring for the shutter blades. Apart from the grease on the main drive and its neighbour unit, the rest of the shutter didn't really seem dirty or greasy at all. But I know there is something to be gained by cleaning old things like these anyway.
And I'd say I have the required confidence, now!