[Leica] LTM to M adapter doesn't quite work

[boulanger.croissant at gmail.com (Peter Klein)]

I was checking various lenses on my M10-P today, and discovered that one 
of my LTM to M adapters doesn't quite work.? It's a 28/90 adapter, not 
encodable, probably Voigtlander, but made before they branded them.? It 
has worked well on my previous Leicas, both film and digital. It was 
always a little more reluctant to click into place than my other LTM/M 
adapters, and I think that may be the problem.

On the M10-P, the adapter mounts, and the lens selector lever moves into 
position. The rangefinder appears to focus. But the camera's lighted 
framelines never appear.? And when I try to take a shot or go into LIve 
View, the camera's LDC screen tells me that no lens is mounted.? I've 
also seen a message in the viewfinder that looks like "bc."

This happens only with this one specific adapter, no matter what lens is 
attached to it.? My guess is that it is not quite turning far enough, 
and something is not happening that the camera tests for its "Is a lens 
mounted?" routine.

Could I remedy this problem by filing something down slightly on the 
adapter? (Probably the stop that halts the lens from turning further 
when mounting).? Can anyone point me to the place to file, or an article 
that describes it??? And would? be advisable, or should I just spring 
for a new adapter to avoid messing something up in the camera?

--Peter