91 bayliner 5.0 mercruiser dies shifting to reverse

[88TransAm]

Hi there everyone. Im new to boating but have been around a few and worked on a few as well. My 91 Bayliner capri 5.0 mercruiser dies in reverse and sometimes eventually will not start. Sometimes it will die shifting from forward to neutral. Never any issues shifting shifting to forward gear. I noticed the wheel on the interrupted switch was not in the V groove in each case. After manually putting it there. It started right up. So do I need to adjust the cable or replace? If so how do I go about doing so. Not a boat mechanic but I am reasonable knowledgeable and work on all my own stuff. Cars trucks sleds bikes etc
Any help or instructions would be greatly appreciated. Like to solve this problem before I put the boat away for the winter. Thanks

 

[alldodge]

Might need a lower shift cable replacement, but do need the shift interruptor adjusted. Go thru the adjust procedure

 

[88TransAm]

Thanks for the info and the attached thread for interupter switch. Much appreciated