1. On my Minn Kota Maxxum the plastic directional indicator broke. When I installed the new one it also broke in the exact same place. Part of the shaft that fits on the spline piece in the head snapped off. The part in the head with the 4 splines seems ok. What am I doing wrong?

You are worried about the directional indicator. Just kidding..but really am not. In time, you won't care if it works or not.

I'm glad this was not what it seemed like to start with.  When I sold my Stratos years ago, the guy buying it commented he had never seen a boat with turn signals on it.  Puzzled, I asked what he was talking about.  He was looking at the tilt/trim control lever on the side of the steering wheel and thought that was a turn signal lever.

 

As for the direction indicator on your TM, about all you can do is make sure it's not binding on the hole going through the cover.  Never had one to break off but I've had them strip out for what seemed to be no reason at all.