1993 johnson shift control arm has a lot of play

I have posted before here with much help so here i will try again. 1993 javelin 379t with 1993 johnson 150 siver series(elatr model) The shift control has a lot of play from side to side. I can move the arm in and out at least 1/2" to 3/4" i know the control box is on the backside inside the boat just the arm is on the outside of the boat it all seems tight from the outside. i took six screws out that seems to hold everything in place but i could not get it thru the hole to look at everything on it. This is just a single lever for shifting and throttle and at the base of the arm is the button you push to engage just the throttle part of the control box. It seems as though i shim or washer or something is missing or deterated somewhere. I can't find or don't know where to look for literature on this. Any help?? thanks.