A quick diagnostic trick is to epoxy a 1/4" flat washer onto the top of the switch button. One of two things are likely to happen- - - -the problem will be solved if the button isn't being pushed far enough, or the starter gear will grind if the motor begins to turn before the drive gear is fully engaged in the flywheel teeth.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!