I have a similar issue with my Hobie Tandem Island. Bit different.
The tiller handle broke off while off-shore in the Atlantic Ocean yesterday....
I did a jury rig at sea by tying some kite line around the tiller handle (so I would not lose it overboard) and pressing down on the tiller handle. Not fun but it got me back safely to port.
A brief inspection at sea confirmed the stainless steel bolt that holds the tiller handle to the metal tiller axle broke cleanly off just above the axle attachment point. Looks like a combination of corrosion and a flaw in the bolt combined to fracture the bolt.
Problem - the broken off bolt is embedded in the axle mount point.....need recommendations on how to remove the portion of the bolt that is embedded in the axle attachment point. See pictures to illustrate the issue.
Broken Hobie Tandem Island Tiller by
Jim Powers, on Flickr
Broken Hobie Tandem Island Tiller by
Jim Powers, on Flickr