Polaris troubleshooting bendix starter shaft makes a rattling sound on the right case cover when above idle

Will the crank shaft turn I would take the plug out and use a 1/4 in exstion and put it in the sparkplug hole needs to be about 10in to were it dont fall down in there and push to make sure the motor is not locked up

Turn over is the process that an engine makes when it is trying to start. If you twist the key and get nothing then it wont turn over. Google shimming a starter and watch the vids.

could be a bad bearing in the cvt cover (assuming its a cvt) replace it with a japanese bearing

have you tested it with a booster pack with the negative clamp directly on the engine and the positive clamp directly on the bendix

I'm in the UK and not familiar with your particular vehicle..
However, the front gearbox as you call it is probably a transfer unit/case. This transfer case takes power from your auto transmission and transfers it to the front wheels.

You can remove the front propshaft (drive shaft) from the transfer case/front differential and make your vehicle 2 wheel drive. This, supposedly, gives you better mpg.

Check to see that the pinion gear of the starter is hooting out and engaging the flywheel.
And if it is working it is possible that you have missing tooth/teeth on your flywheel and the starter cannot turn over the engine because of that.

Disconnect the battery and then carefully remove the starter. Take the unit to a local auto parts dealer for a bench test. Starters have two separate functions, one spins the shaft to crank the engine, the other is called a bendix, which pushes the starter gear out to engage the flywheel, and then after the engine engages, retracts it (except in the case of starter/generator combo units which recharge your battery and power your vehicle's electricals while the engine is running) Always best to get a bench test rather than depending on apparent symptoms.

sounds like your high jet in the carb is either clogged or you have water in your fuel.

sounds like a short in wiring system, from kill switch to your push button start on handle bar