Tiller: Tines won't turn but wheels turn
If the tines won't spin but the wheels move, the problems could be a broken or missing clevis pin on the tines. Another cause could be that the drives and gears in the transmission that control the tines have failed. See the suggested repairs below that might help you resolve a problem with the tines not turning.
These repairs may help solve your Tiller problem:
Adjust or replace the tiller clutch cable
The clutch cable engages and disengages the drive system on the tiller. Test the drive system and adjust the clutch cable if necessary. If the cable is damaged or broken, replace it.
Replace the tiller tine shaft clevis pin
A clevis pin attaches the tines to the rotating tine shaft. The clevis pin is designed to shear off if the tines hit a fixed object while cultivating to protect the engine. Replace the clevis pin on the tine shaft if it breaks.
Replace the tiller transmission
The transmission controls the motion of the wheels and/or tines on a tiller. An internal gear failure in the transmission can prevent the tines from turning or the wheels from moving. Replace the transmission if it won’t drive the tiller components properly.