The shift cable rubs on the engine coupling not the shaft.
routing of the cable is very close to the coupling.
I had to change one on the trailer the second day of a 5 day boat trip.
Had to drive back to the trailer the second day because the drive with the bad cable wouldn't go into reverse.( stuck in forward )

Your mechanic needs an edumacation. Not only should he have swallowed the repair and kept you as a client, he should have noticed the problem, brought it to your attention and charged you to correct it. Get another mechanic!
Bosco

It seems that he's honest to a point and you've found it. Now that he has demonstrated this, you won't be able to trust him going forward. It's not the mistake that is the issue here, it's how he elected to resolve it. Bag him...find another mechanic

Ditto!!!

It's amazing how some of these boat mechanics lack common sense. Hope it was worth an hour of free labor to him to lose a customer.

Thats what my thoughts are at this point. I think Im going to try another mechanic that was suggested by another member on here and give them a shot. Its a little bit of a hike to get the boat to him, but I dont mind that for a little piece of mind knowing it was done right and honestly. Thanks for all the input guys.

I agree with you on this one,,, and thats what I did, the mechanic is myself. It will have to be a drive or someting drastic before I take it to another mechanic. I let the reputable machine shop do the machine work and I do the engine and electronics.