It is highly unlikely that the motor is shot. More than likely, you are not putting enough torque on the motor to make it rotate. Bad motors on tillers are something I have never heard of on any forum in the past ten years. Someone would have to drain all the oil out, allow water to fill up the motor and then leave it sit for years. The motor is protected by the relief valve in the PTO every bit as much as that same relief protects the pump from damage. If you are still concerned, then why not plug the hoses into your tractor's PTO valve and run the motor by itself to give you some peace of mind prior to re-assembling the tiller.
Are you putting a brand new length of #50 roller chain into that chain-case? Make sure you wash out the chain-case and clean everything meticulously and then heavily coat the new chain with chassis grease. When you get ready to install the other half of the case, fill the first chain case half with chassis grease until the grease is level with the chain. Then close it up and bolt it together. Go around the case and tighten the bolts a couple of times
Are you putting a brand new length of #50 roller chain into that chain-case? Make sure you wash out the chain-case and clean everything meticulously and then heavily coat the new chain with chassis grease. When you get ready to install the other half of the case, fill the first chain case half with chassis grease until the grease is level with the chain. Then close it up and bolt it together. Go around the case and tighten the bolts a couple of times
