Throttle only button 1998 Ranger Cherokee 90 hp Mercury 2 stroke

[basement pro]

I have a 1998 Ranger Cherokee, 90 hp Mercury 2 stroke with the quicksilver 3000 control unit. The throttle only button has stopped working, when you depress the button it just slides all the way in with no tension and won't pop back out, it also isn't allowing it to go into neutral. I am assuming that the plastic shaft inside has broken off? My dilemma is finding the right part online to purchase and directions for replacement. Any help is appreciated.