5hp (manual) Starter not engaging 1985 Mariner 5hp

[baptistpreach]

My pull rope will engage the flywheel, but only for about 4 pulls, and then it starts spinning without grabbing. I have to take the flywheel? off (3 bolts) and re tighten the nut on the underside with a few pulls with observation to make sure the yellow plastic gear engages, and then it will work again under load for about 4 more pulls and then it starts slipping again.

There is a nut on the top of the starter as well, and there's no washer on it, is the problem that it needs a washer to help it hold in place? I'm hoping for some help here, thanks!