The sealing rings are synthetic resin with chamfered ends. Check the condition of the sealing rings, and replace them only if they are worn, distorted, or damaged.
For a better fit, squeeze sealing rings together slightly before installing them.

Apply ATF to the new sealing rings, then install them on the secondary shaft.

After installing the sealing rings, verify the following:
The rings are fully seated in the groove.
The rings are not twisted.
The chamfered ends of the rings are properly joined.
Installation
Hold the gearbox housing using a C-clamp (A) and wooden blocks (B) to a
workbench as shown. Do not clamp the cylinder part of the gearbox housing in
a vise.
...
Emissions Testing
Testing of Readiness Codes
If you take your vehicle for an emissions test shortly after the battery has
been disconnected or gone dead, it may not pass the test.
This is because of certain ‘‘r ...
Pilot Bearing Replacement
Remove the crankshaft pilot bearing (A) using the remover weight (B), and
the 15 mm bearing remover shaft set (C).
Install a new pilot bearing (A) into the crankshaft using th ...