action reg puzzler on M & H BB

[Ric Brekne]

Ed writes..

    If the hammer is getting caught by the back check on the way up,
    that means
    you are probably probably hitting the key before the jack has a
    chance to
    reset under the knuckle. 

This is a grand yes.... ?  just what will be pushing the knuckle upwards 
to be able to jam the tail into the backcheck if the jack is essentially 
missing ?

I like Moffatts guess best so far... only thing that seems to touch on 
the the problem... at least as I think I understand its wording.

Cheers
RicB