Mamiya Super 23 + 50mm f/6.3

Hi there. Please move this thread if it belongs elsewhere.
I just received a 50mm f/6.3 with the bayonet fitting for the Mamiya 23.

However, when I first loaded the lens and locked the bayonet it would only focus from zero to abour one metre before it hit something hard. I removed the lens and tried a few times before setting the focus ring to infinity. Now it focused as expected but when I got down to a metre something clicked and I was stuck as previous explained. When I removed the lens and set it to infinity it again focused infinity down to about 1.0 metre before it clicked.

Also now I notice that when inserting the lens into the bayonet I really need to dip the back element under that sprung metal thing and again all is well until I drop to less than a metre.
Is this a problem of using less than 65mm lens ?
Truthfully I don't really understand what that spring feeler does because on a 100mm lens using the rangefinder it does not seem to do much.
Could I safely disconnect that part as I intend to use a ground glass focus screen before swapping in my roll film back.
Thanks for reading.
 
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