Compur Rapid slow speeds hang open.

[zanxion72]

The Compur Rapid shutter of my lovely Zeiss Ikonta 521/a hangs open at the settings 1/15 or slower (B works fine). Is the shutter damaged, or just gummed up? Is this easy to fix, is there a guide opening it up?

 

[shutterfinger]

It needs a CLA. Compur shutters are a 8 to 9 on a scale of 10 in difficulty for a beginner with very good mechanical skills.
http://benoit.suaudeau.perso.neuf.fr/manuels_rep/obturateurs/Compur-shutter-repair-manual.html download all the links in the lower section and install the DJVU reader to use them on your computer.
Your camera model is not listed but Compur shutters are similar in design and function. I have serviced Compur Rapid shutters that were not listed using this manual. On one shutter the aperture and shutter blades (below the center plate) were identical to one shutter in the manual with the top of the center plate (cocking, delay timing, speed ring, top cover) were identical to a different shutter.
The camera body and how to remove the shutter from the body are not covered by this manual.

 

[zanxion72]

Thank you so much for that link. Indeed it looks complex for a beginner to fiddle with it. I will have a through look at it and if it seems out of my reach, I will send it for CLA.
It looks like new and it would be a pity scratching it with a low possibility for a successful outcome.

Thank you!

 

[Svenedin]

I have DIY serviced shutters and I can't say I have found it enjoyable. The main problem is that whilst it is possible to clean out gunk there may be other problems as well. I have spent hours cleaning shutters only to find that parts are broken or worn out and I am unable to fix them so it would have made far more sense to have sent it to an expert in the first place. Once the mechanism is clean it needs the proper lubricants in all the right places (some shutters use no lubricants though) and then to be tested to check that the shutter speeds are accurate. As the Compur shutter was used in many different cameras and over a long period of time it isn't that difficult to find someone to fix it and if it is just dirt then it should not be expensive either. I'd suggest you take it to a competent repairer and then you can enjoy using your camera again.