MILES58 - Last night I worked on my old Win M12.
First I got the correct screwdriver for the job.
Took the magazine tube apart without difficulty.
It did have a dowel for a plug. Everything looked
okay and I put it back together. As it turns out,
that was not the problem.
So ... it must be the shell stop.
Looking into the bottom of the receiver I can see
the shell stop. It is marked '16' and it is clearly
jammed. It maybe also worn or broken.
The shell stop is the problem.
Next question --
How do I remove the shell stop ?
Thanks for your help.