The button from my automatic shifter just fell off one day. It looks like the plastic of the button's shaft has basically deteriorated.
I tried to glue it on and that lasted a couple of weeks before it fell out again.
Is there better way to reattach it? Do they just sell this part for me to replace in my own?
I've been just digging my thumb into the hole to engage the button.
Is there a hack for this? Can I just mold my own button by pressuring sculpy into the hole?
Replacing the shifter is probably the only "proper" fix you can make.
If it were me, I would go down the route you suggested - make your own button. There is a really cool product called Sugru that would be ideal. It's essentially modelling clay that hardens into firm rubber in about 24 hours. It bonds really strongly, so will definitely stay put. Make sure you clean the area with something like rubbing alcohol first.
Just guessing from the picture, that the plastic shaft is approximately 8mm in diameter. So, why not drill the chromed button and either tap a thread into it then glue a cut-down bolt or glue a hard plastic shaft into it?
After more research, I actually found that you can just get the replacement shift button on Amazon. I then searched for an instructional video on YouTube.