Help needed, Nikor 5cm 1.4

[AlwaysOnAuto]

I've been having a blast with my new old NEX 7 and the adapted lenses but have a problem.
The Nikor 5cm 1.4 is now exhibiting a 'tough' spot on the focusing.
It happens about 1/3 of the way around from the infinity lock position in a counter clockwise rotation. Does that make sense?
If infinity lock is 12 o'clock high by the time it gets to 8 o'clock it's sticky/hard to move. I can get it to go past the tough spot but don't want to hurt anything.
Is there a transition in the helicoid at that point?
It almost feels like it's going from one 'gear' to another or something is moving past a snug spot.
Any ideas?
TIA.

 

[ferider]

If this is the 50/1.4 LTM, and the rough spot is at around 1m, this is a feature, not a problem (to tell the user when the RF de-couples).

There is a bracket with two screws on the outside of the lens. When you take this off, the rough spot disappears (the bracket puts pressure on a small ball bearing).

Roland.

 

[AlwaysOnAuto]

Thanks Roland, it is the 50/1.4 LTM and yes that is @ where it takes place. It is about midway between the RED 3 and BLACK 3.5 on the focus scale.
Glad to know there isn't something wrong with the lens.
User ignorance can be cured!