I know this is an older post, but someone may have need of this information again:

Just a note, if the damaged swing plate has been in the machine a while it might have damaged the main drive. (Sometimes you meet a gem of a client that decides to wait to call a tech because "it's noisy, but it still works." If so, you will end up having to replace the Main Drive. ) Main drive > Swing Plate > Fuser is the way the machine is set up. If you have changed the fuser and the swing plate asm and you still have noise the main drive is your next step.

IMO, the LPR bushing is the culprit in all of the 42xx/43xx swing plate issues. The bushing gets worn, the LPR starts to wobble, and then the fuser gear damages the swing plate gear. If you are just replacing the fuser gear, make sure you replace the LPR bushings at the same time. Otherwise, you will probably have this problem again. Some techs like going out every other month to change the swing plate. It's up to you. I do not.

I have attempted to attach step-by-step instructions for replacing the swing plate assembly in the this machines. Hope it helps.