Check the play of the release bearing by spinning it by hand. If there is excessive play or noise, replace the release bearing.

NOTE: The release bearing is packed with grease. Do not wash it in solvent.
Reverse Shift Fork Clearance Inspection (M/T)
Measure the clearance between the reverse idler gear (A) and the reverse
shift fork (B) with a feeler gauge (C). If the clearance is more than the
service limit, go to step 2.
...
Indicators
...
Inspection
Raise and support the vehicle.
Remove the front wheels.
Check the thickness (A) of the inner pad (B) and the outer pad (C). Do not
include the thickness of the back ...