Thanks for this. Is it possible to “easily” inspect the area where the old seal has been? and if not easy, what’s the best way to do the inspection?
A small mirror like a dentist's mirror can be useful. The new cheap flexible borescopes like the Vividia should be useful,too.
Do the replacement seals come with a spring? or is the existing one reused? Interestingly, I don’t see the spring listed in the parts list?
As Skywagon said the spring is part of the seal. The spring gets removed for installation for both the split seal and the one piece seal and then reinstalled. You may end up making tools out of safety wire or loops of dental floss or such to hook and maneuver the spring ends for reassembly. Somewhere I saw a suggestion for covering the prop hub with a plastic bag and lots of lube for one piece seal installation, the idea being to protect the lip from damage as much as possible. So far in my limited experience split seals have worked just fine when you follow the directions.
Also check the parts book carefully by model and serial number. Some engine/seal combinations use retainer plates after the seal is installed. The retainers and an unobstructed vent line would eliminate the possibility of a seal blowout.