OP

Quoted from nhislop:

Swapping out the main bracket assembly of my Doctor Who (managed to get a replacement via Pinside - woohoo!), the issue is that when I run through the MPF self-tests, when the playfield is in the middle position (specifically, after executing "CCW MID L") it settles in a position where it is slightly too low, the upshot being that when the ball is aimed at the opto targets it is impeded by the lip of the MPF, so doesn't strike the switches / register the hit.
I notice that if I lift the MPF by hand from that position, there is a little play in the mechanism; if I pull it up as far as it will go then the optos are in the correct place.
So, why is there play in the mechanism?
Here is a video that shows you what I am dealing with:

It looks to me as if the set screws joining the cam to the motor are tight; I would have thought that if that was the case then nothing could rotate, and in fact to my untrained eye it looks as if the "D" shape is not rotating, but that doesn't seem right, as the cam seems to do so a little bit.
I swapped out the motor a few years ago, FWIW.
Any help appreciated!
Does anyone have any tips / tricks?