If the wheels on your tiller move but the tines don't spin, you may need to replace tine shaft clevis pins or replace the transmission.
The tiller's transmission drives the wheels and the tine shaft, so you'll likely need to replace the transmission when the wheels spin but the tine shaft doesn't move.
If the tine shaft turns but the tines don't spin, check the tine shaft clevis pins. The clevis pins are shear pins that connect the tines to the rotating tine shaft. The clevis pins are designed to shear off if the tines hit a fixed object during cultivation to prevent damage to the engine and other tiller components. Replace broken tine shaft clevis pins to restore tine rotation.