props spins when trans in neutral

I have a 77 Tique. I have had another new transmission put in last year as the old one would not go into neutral or reverse. In fact I have had about 5 transmissions (i know that just crazy, but I'm crazy about this boat) put in, in the last several years. I always know its starting to go bad when the button is pulled out in neutral but the prop is still spinning and wants to go forward. It just started doing it again. Does anyone know what keeps going wrong and how to fix it? Thanks

I have not been putting this in myself. I had a dealer do it. This last one they also changed the flex plate thinking that might be what causing it. What is the linkage? Could it be the stringers are bad?

The stringers don't have a whole lot to do with the trans linkage and I wouldn't trust a dealer to fine tune the linkage.

Follow the transmission control cable to the shift lever on the trans body.

Unhook it from the transmission.

There are 3 positions on the transmission shift lever and you should be able to feel them when you move the lever forward and backwards.

All the way to the bow is in gear (forward). All the way to the transom is in gear (reverse). Between the two you should feel center (neutral).

If you have to pull the lever forward or back when connecting the control cable then you'd develop the dirty neutral (prematurely engaging forward or reverse when it's supposed to be in neutral)

When I rebuilt my Tique I had some trouble with the linkage and had to bend the control cable mount ever so slightly to attach the cable without moving the shift lever.

I think I get it, do you mean that I put it in neutral (unattached to the cable) and when i put on the cable back on to the transmission, the cable needs to meet it at exactly that point.

Thanks!