starter gear is to close to flywheel install starter shim

The starter celinoid is attached to the starter itself.

On top of starter

Disconnect the negative battery cable from the battery, remove the two bolts from the starter, drop the starter enough to disconnect the wires from it and remove the starter from the engine.

if the starter is spinning but not engaging then the bendix (starter teeth) is not moving out to grab the flywheel teeth or the flywheel has some broken teeth. The starter needs to be removed to see what the issue is.