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.
Transmission End Cover Removal (A/T)
Special Tools Required
Mainshaft Holder 07GAB-PF50101
Remove the bolts securing the ATF inlet line (D) and ATF filter holder
(E), the line bolt and sealing washers, and remove the ATF in ...
Manual Transmission
The manual transmission is synchronized in all forward gears for smooth operation.
It has a lockout so you cannot shift directly from fifth to reverse. When shifting
up or down, make sure you pu ...
Cylinder Head Inspection for Warpage
Remove the cylinder head.
Inspect the camshaft.
Check the cylinder head for warpage. Measure along the edges, and three
ways across the center:
If wa ...