Looks very thorough...
the only thing I would comment on About the deck mandrels that briggs mentioned... It's hard to tell how bad they are with the belt tensioned, If possible loosen the belts to allow a feel of the bearing condition.
This may not be easy to do on a lot of riders, but I have seen shot spindles seem good and snug with the belts holding everything tight...
And while thinking of unloading shafts and spindles... If you can raise the wheels to allow for a check of axle bearings/bushings...
You can't cover everything in a general check list ... BUT I think you have hit on about everything conceivable and checkable... Great post... :smile:KennyV