Small Engines (Lawn Mowers, etc.): cant get rider to crank, safety plug, brake safety

Question
Have a '96 MTD w/ Briggs engine. Battery and starter both good. Already replaced solenoid, ignition switch, clutch/brake safety plug switch, also checked blade safety plug and seat safety. Nothing seems to be working. Did notice brake rod seemed loose. Only getting high pitched grinding when the key is turned (kinda like starting a car that's already running) What else could keep it from turning over? Thanks.

Answer
 Hello Dom:

 It sounds like you need to Replace the Starter Drive Gear on the Starter. The Starter Drive Gear is made of Phenolic, a type of Hard Plastic. Thats the high pitched grinding you hear.  Hope this Helps.

 Good Luck

 Respectfully

 John