50mm cf with focus "arm" issue

[davecarrera]

Hello All
first post so please be gentle lol.
I have a 50mm f/4 cf which to my uneducated eye seem to have have the focus ring replace with a "arm" or lever with "Hasselblad one" written on it.
It looks like it is a true item as it were because the ring has "half moon" shapes that match up with the lens metal body it slips onto.
My issue is that it slips off easily making it close to unusable for focusing and I wondered if you guys might have a working solution other than superglue.
It seem to originally have some kind of foam strip inside the ring which has perished leaving just the residue.
Wishing you well and happy shooting

[Georg Kovalcik]

There should be a screw which can be tightened. Can you post a photo of that focus handle, to see which type it is?