How do I remove and replace the starter bendix properly?

Depends on type of starter motor, some have a bendix some are pre engage.
If bendix the shaft may need lubricating to allow the dog to move.
If pre engage type, check for a faulty solenoid.

Inspect your starter motor. If the starter solenoid is gummed up it won't engage properly. It was probably the cause of the initial fault and consequently damaged the ring gear and bendix, or excessive wear caused the bendix to fail. Swap the starter for a good serviceable unit or get yours rebuilt. Also check your ground leads for solid connections to your engine and chassis and your main battery terminal leads as well to ensure your starter motor is getting full current. If all of the transmission bolts are tight and the starter motor is bolted in properly that should eliminate the issue of poor starter gear alignment.

The bendix is at the top of the starter. Pull the starter, remove the four bolt at the back of it. Pull the cap off the starter. remove the clip on the end and pull the bendix out.. Just a note.. they quit selling bendix and solenoids years ago.. Starter only, all or none.

What is year--make--model of vehicle?
Some starters you can take it off and lay it on the ground. Hook up jumper cables properly from starter to fully charged battery. At the least, it should kick out the drive gear and spin. That is a no load test. Some of the national brand auto stores will test the starter for you.

Did you check voltage and ground circuits at the starter motor. Any testing at the starter, make sure tranny is in park or neutral and the parking brake is set.

Part of the starter is the "bendix spring". If that's broken, the starter's gear won't retract from the flywheel, and the starter will keep running. The solenoid may not be properly engaged with the bendix spring, that may also be a cause.

could be bearing in starter or drive gear not properly engaging your flywheel's teeth. remove starter [note, some auto retailers will test your loose starter at no cost]. secure starter and briefly spin starter using jumper cables. 'bendix' gear should extend quickly, if not replace bendix or starter. if bearings quiet, inspect teeth on starter. if all ok, inspect flywheel edge for worn or missing teeth. if all ok, you may have an incorrect starter for your car. if correct starter you may be able to remove or insert spacers or washers to alighn gears.

Hello: The bendix may can be replaced but it may be cheaper to replace the starter but before replacing the starter or bendix check and make sure the teeth on the flywheel are not worn off. Really need to know the year and model and engine for proper diagnosis.

Sounds like the Bendix... You might ought to pull the starter and look at the teeth on both the bendix of the starter and the flywheel. If the teeth on both are in good shape...then its probably a weak starter not throwing the bendix out to turn the flywheel. But...if the teeth are **** up on the bendix...its cheaper tp replace it. Make sure Battery is in good condition as well. Both battery AND starter can be tested at your local AutoZone... Hope this helps...

Make sure to check the flywheel when you remove the starter there may be flywheel damage and that would cause the same problem.

If it just spins when you turn the key, either the Bendix gear is not kicking out the starter gear, or the flywheel/flexplate hs broken or missing teeth. Was the old starter 'shimmed'? If so, did you put the same number of shims back in when you installed the new one? It is possible your starter, even though it is new, is not working properly-rebuilt units can be defective out of the box.