Horn not shutting off

[Pinkdubai]

The truck has an aftermarket shaft put on by the previous owner. I’m not able to find any details regarding the manufacturer. As noted by Richard, I also have a one piece hub and cap from Forever Sharp, which fits the splines better but still results in the turn signal cam being compressed too far. It seems like I’m missing a piece that prevents the turn signal cam from sitting directly on top of the turn signal mechanism.

Appreciate all the comments so far.