Only thing I can think of is a problem with the shifter-gearbox alignment. Possibly some mounting point is giving up, though that would be quite a strange issue.
This seems to be affecting three different collars but only on one side of the 1-2 and 3-4 collars (6th is it's own apparently). That is leading me to believe something has caused the gearbox or shifter to be misaligned in the longitudinal axis.
There's a good YouTube video here describing the internals