New Holland Super 68 Knotter problem

OK, so my rebuilt Super 68 went out for the first time yesterday and baled 300 nice tight brick without a problem. Then BANG, followed by a louder BANG,knotter bill as first the knotter shearbolt popped, followed by the needle safety latch not moving out the way and the main shearbolt popping as a result. <Expletives deleted!>

Had a look round the knotter assembly and the nearside knotter seems to be having a problem. The entire knot of the previous bale seems to have gotten itself hung up on the bill hook rather than sliding off which caused the string on that bale to snap. I think it then jammed the next bale and prevented the bill hook moving through the cycle which blew the shearbolt.

Cleared all the string out, replaced the shearbolts (the knotter one is a real fiddly little sucker), ran through a cycle by hand to make sure everything was moving smoothly and all was OK. Did 10 more bales and BANG, same thing again!

Clearly everything is kind of working but something is a teeny weeny bit out. I'm check my rather poor copy of the knotter manual and scratching my head. Wondering if the billhook is worn or rough and that is the cause of the string not slipping off. Before I go down the route of pulling things apart this morning thought I would tap into the collective expertise here to see if more experienced folks than me have experienced this before and can fast track me to a solution.

Thanks in advance

on the NH-JD type knotters the twine wiper is supposed to come across and "wipe" the knot off from the bill hook. My MF has no twine wiper to get out of adjustment so when the knots get hung up on the billhook the problem is the twine knife. My MF had this problem at the very end of last season, and sharpening the knives this spring cured it. You can't trouble shoot your baler by running it through one cycle by hand. You need to take all the tension off and remove most of the hay from the chamber and run it by hand multiple cycles, in order to see exactly what is going on. It is very unusual for a knot hung up to cause a main bolt to shear. Before going back into the field get twenty good ties by running it from the tractor, and tripping the tie, feeding a little in, tripping the tie, feeding a little in....

The plate with the curved notch is supposed to rub the bill hook to strip the knot. Unbolt the lower end and flip the knotter up and you can see the wiping action. You
adjust by bending the lower end of the stripper arm so the notch contacts the bill. If there's a gap there it will pass over the knot and leave it on the bill. The next
bale will tie right over it.

steve check the bushing that runs around the inside of that knotter.. those bushings get flat spots and can cause what
your talking about.. they will run a while then hit the flat spot and boom..
just one other thing and a easy fix if they have flat spots..

Steve, which bushing are you talking about. The top end of the stripper arm has a brass ball and the bill has one too. Both can get flat spots. This is the bill hook I replaced.

Can't get the picture to post

(quoted from post at 05:53:38 08/04/20) The plate with the curved notch is supposed to rub the bill hook to strip the knot. Unbolt the lower end and flip the knotter up and you can see the wiping action. You
adjust by bending the lower end of the stripper arm so the notch contacts the bill. If there's a gap there it will pass over the knot and leave it on the bill. The next
bale will tie right over it.

Click to expand...

The wiper is supposed to contact the bill hook with a certain amount of pounds pressure but I forget the exact figure. In any case the wiper will not do the job if it is merely close, it has to be firmly rubbing the bill hook.