Bearing replacement on tiller

[Mace Canute]

Drill two holes in the sprocket (three would be better), thread them and use a puller.

 

[Tractorrr]

Can you get that C clip off with a pair of pliars or needle nose pliars?

 

[dpb800]

I second the puller.

 

[davesl708]

The key should be softer metal than the sprocket or shaft. A three prong puller should pull the sprocket off the shaft.
Another option if you have room between the sprocket and frame to get a pipe wrench on the flange of the sprocket and block the shaft so you can get the key back in the key way.

 

[skyhook]

Yea it definitely twisted. Any recommendations on turning it back?

You could take a plumbers pipe wrench on the shaft of the tiller,
give it a few good shots, backwards while someone watches the key way.