i've got a bit lost here ,
is your concern that the hammer can rotate and therefore possibly strike at a different part of the face ....which may be un square and give un equal hits ?
just check for square and face off if needed
cocking roller rubbing the hammer stem ?
we had this on robs .....it wasnt the roller , it was the screw ......face it down a bit . edit if it is the rollers .......set the seat a bit deeper into the stabilizer body
important to make sure the cocking roller screw is secure , robs came loose a lot .
intresting to note that the double slot chassis will bend a lot if the screws are overtightened ........would be interesting to investigate whether the block can do the same ....maybe to a lesser degree .....and distort trueness of the hammer tract