Leica IIIf BD SYOOM compatibility

Neither of my IIIg SYOOM baseplate winders will mount on my 1951 IIIf BD from the 30K production block. Although both SYOOMs fit on the bottom of the IIIf, neither can be locked in place with the SYOOM marked "auf" and "zu" rotating locking tab. Both lock easily on the IIIg bodies. Is a IIIg SYOOM supposed to be a compatible retrofit on IIIf BD cameras or is there a reason they will only fit on a IIIg body?

4 days without and answer. I hope I don't violate Photo.net forum etiquette by suggesting you post the question on another site; the Leica Collectors and Historica forum. I think your question is just a notch too specialised here.

It may be a good idea to include a photo. Not that I doubt a collector would know what a SYOOM is, but sometimes Leica made changes although they kept the product code. For example, I had some compatibility issues with a FILCA and found out that there are 4 different FILCA versions.

4 days without and answer. I hope I don't violate Photo.net forum etiquette by suggesting you post the question on another site; the Leica Collectors and Historica forum. I think your question is just a notch too specialised here.

It may be a good idea to include a photo. Not that I doubt a collector would know what a SYOOM is, but sometimes Leica made changes although they kept the product code. For example, I had some compatibility issues with a FILCA and found out that there are 4 different FILCA versions.

 

Your reference is a good one. There are several regular participants of that forum whose knowledge is encyclopedic and will go to great lengths to provide an answer.

Thanks for your guidance and advice. I hope someone over on the other site has an answer. I may be in error thinking there is only one version of SYOOM.

Although not answering your question directly, here’s some more info from the Leica Wiki site:

 

SYOOM - Leica Wiki (English)

 

The forum discussion links may reveal something more specific.