CV75/2.5 Heliar loose focussing ring

[TMLee]

The focussing barrel keeps unscrewing whenever I focus 'beyond' its limit.

What do I do to make it stay ?

Tried tightening but it still comes loose.
Is this a known QC problem? Googling throws up some remarks to imply that this is a known factory design weakness.

If glue is the solution, what should be the correct kind ?

Thanks in advance 🙂

 

[ampguy]

There's a new one out, the 75/1.8, time to upgrade!