We had the same problem, resolved fitting a piece of dowelling up the hollow tiller drilling the tiller and wood with suitable sized holes (not right through tiller) and pushing in aluminium nails with large flat heads. The latter have the advantage that they lie flush with the tiller stock and don’t get snagged on the main sheet/trousers etc. Two is better than one in case comes out. Friction holds them in, screw driver blade prises them out.
Good luck,
Nick 9922