"Wayne" wrote:
The starter on my O-360 is not releasing when I let go of the starter
button.

Cause: grease from the starter's gearbox gets forward of the grease
retention plate into the Bendix and gums it up.
Easily fixed in less than an hour.
Remove the starter, take the Bendix off, clean its shaft and housing with
Stoddard solvent (kerosene), dry completely, lube with Teflon or silicone
spray (no oil or grease), reinstall.
Do this every few hundred hours, and it'll always engage fully and disengage
immediately.
Defer it, and it won't engage completely (causing uneven wear and early
replacement of the Bendix and ring gear), or won't disengage (likely
breaking teeth on Bendix and/or ring gear, or destroying the Bendix or
entire starter).

Also inspect the teeth of the Bendix and ring gears. Sticky Bendix might
not extend to completely engage these gears, causing scoring or uneven wear,
which can prevent completely engagement and lead to broken gear teeth.
Minor steps in the aluminum ring gear can be dressed out using a file. If
the Bendix gear is scored, it's $50 for a new one from Chief.