Bobcat m444 not moving left or right, shaft spinning freely?

[Jesset1234]

Hey all, 1963 m444, not moving anywhere, engine starts and revs fine. The front pulley/sheave just spinning freely on the shaft. I removed the belt and slid the sheave/pulley to the side and revealed the shaft, there is no rectangle key on the shaft, and its a little rounded off. Any issues of replacing the key, tightening the set screws and then welding the pulley onto the shaft? Just looking for ideas here