Yes indeed,the earlier decks were more robust.I guess B&O needed a "universal" mech to use across the range,and the later job was obviously cheaper to make too!!In fairness,it works well normally.
I can't point you directly at a suspect part,I think it's that the tolerances of the plastic gears are fairly variable.I fiddled about driving the mech through it's cycle manually,and watching what happens,then managed to tweak it to work properly.
Don't touch the head alignement if you can possibly avoid it,it's rarely out unless someone has previously jumped to the wrong conclusion!
I may have some notes about this problem from B&O too,I'll sort through the "vaults".
Regards,
Nick