May be of use... I had an issue when replacing a speedo gearbox in a hurry, I didn't notice that the cheap 'metal' in the speedo boss had separated from the body (yes I know!) - thus creating an extra washer (it was covered in dark grease/oil from chain & stuck to the washer - 06.5549), this caused the disk to bind on the caliper as the axle was tightened. So back to conscious competence, clean & lay stuff out clearly in good light & take one's time!