OK I see the point on the line release, ours gives a lot of leverage so the spear does get pushed even with low line tightness hence the stainless pin to stop it moving but the propeller type has even length both sides of the pivot point

cool thats the way we will go on the next batch

Now these shafts, with the recessed one I have, its pretty smooth on the sides but the top of the flopper sits about 1.5mm above the shaft, we've had a look at it and decided that we can knock it down a bit at the front to close the gap without affecting its operation, are we on the right lines? Also on the bottom of the flopper the two sides stick out doen beyond the bottom of the shaft, should we file these bits away too?