Everyone needs to keep a spring removal hook under the bench, Witzend. I made mine years ago (in 5 minutes flat) because the alternative was to risk getting hurt, then and in the future:
[Linked Image]
[Linked Image]

I think there was a crude alternative to replacing that cutter disk. I'd probably have wasted half an hour truing it up then balancing it (it would have required balancing because by the time it was straight, the center of the disk would no longer have been in line with the center of the shaft). However your method produced a better job.

I suggest you spin it up on the bench before you put it back in the mower, in case you've Brinelled one of the bearings.