Hi Tim,
Those photos are much better and it confirms what I originally thought. That clutch has been scrounged from an earlier machine and put onto yours. Your machine shouldn't even have a cotter as it is a Rover 45 and not a Scott Bonnar. The clutch has been taken from a mid to late 1970's SB.
Anyway I would not use it any more with a loose captive cotter pin and put a later style new clutch body on it that uses the two set screws. If you are going to replace the motor then I would do the job all in one go.
As far as the reel clearance is concerned I would first try to close up the gap between the reel and bed knife and see what result you get from that. It looks like the bed knife was changed not too long ago but whether it was machined prior to fitment I can't see at that angle of your photo. See if you can provide us with a photo looking at the top leading edge of the bed knife and we'll get a better idea.
Cheers,
BB.
