Fed 50 collapsable lens question

I tried the Fed 50 collapsable on both my Zork 4 and Fed 2 and I can`t get the dual image to converge at infinity however close focus at 1 meter is fine or at least very close.

I had previously adjusted my fixed lenses for infinity and they do not seem to vary significantly when I switch.
Is this normal to have this difference in these two differently designed lenses? And how do I approach the remedy?
Thank you,
John

I just discovered another potential problem. If the RF tab inside the lens mount sticks down a bit it can come into contact with the locking tab of a collapsable lens.
The tab on my Fed 2 is lower than the tab on the Z-4 thus making contact when I collapse the lens. I have to turn it slightly to miss the RF tab.
Seems I will have to take my thumb and gently press the tab up towards the edge of the lens mount ring so those tabs on the lens clears. Is this advisable?
Thank you,
John
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Strange. Fed 2 many years was produced with collapsible lens. May be you have very early FED lens what had different set up?

OK, So I guess I had a legitimate situation here and Wolves from the RF forum seemed to have an appropriate solution to all my concerns.
I`d like to post them here just for general information to everyone.
John

"Collapsibles often won't work on a body that didn't come with one originally. Bodies using collapsible lenses have a thicker lens-mount flange to allow for the infinity-lock pin to depress as the lens is pushed to infinity. The cure, if you really want to use the lens, is to remove the infinity-lock pin. Other than that there's no issue.

On the FED 2, as spyderman says, you can bend the RF sensor arm up a fraction, it's common for them to be too low. Do it gently and only bend it a little, nothing should break. Check for correct working on the lens-cam afterwards - take the back off and see that the sensor still rides on the rotating lens cam."
__________________

So this evening I simply unscrewed the infinity lock pin (really tiny) picked it up with a piece of transparent scotch tape and attached it too a heavy piece of white paper and labeled it for future reference and reinstallation should I ever sell the lens.
I gained an extra 4 mm of travel which now allows me to converge subjects/objects on infinity focus.
And I managed to slightly bend the RF cam pin with my thumb about a mm and it is no longer making contact with the lens locking flange when collapsing.
Seems my troubles are solved pending a re-check / readjustment of the RF and a test roll of film.
Hope this helps others who might encounter these problems.
I just want to also mention that the Fed 50 lens that Alex sent me is near mint. Not a scratch or dust spec in the glass or the chrome finish. FYI the lens # is 214204 and I`m not sure when it was made.