n h 640 round baler

I bought a really clean N H 640 auto wrap round baler at an auction Saturday. the auctioneer stated that it DID NOT need a
monitor/controller to use it. i was excited to get it home and start baling as I had hay down and ready. After greasing it up and
oiling the chains, i loaded the string. i noticed the string cutters above the pick up head. never using this style was curious
how it tied with no power. i did notice the manual trip lever. so i figured i'd give it a try, i could always discharge the bale
if it didn't work. when the arrow got close to the stop position i stopped putting hay in and tripped the manual tie. it worked
perfectly. until it would not stop tying. i figured it needed to go through again. i still didnt stop, it started a 3rd time.
when the tie arms got back to the outside position i shut the baler off. cut the string and discharged the bale. i started the
baler and it still wanted to continue tying. i had to unhook the belt off the right side where it spins the tying mechanism. there
is a slide mechanism also on the right side that does not slide back up to stop the dogs on the wheel. DOES this need to be powered
to make it tie correctly ?

No, no electrics are required for an auto wrap to operate. The electric hook up is only for a buzzer on the tractor to tell the operator that the baler is going to tie the bale and to stop forward travel. The auto wrap can be set to tie at any bale diameter. At set size, the wrapping mechanism starts automatically. Really good simple bullet proof system made mostly with NH square baler knotter parts. Your 640 has probably sat for awhile and the twine knives are seized up a bit .The knives are mounted on tubes that go through the side of the baler and are spring loaded. There are two tubes, one for each knife. The tubes run inside of each other and need to be cleaned up and lubed. Go to NH parts and look at the exploded view. A owners manual would be good as well. Hope this helps. Great balers..........Ron

PC 1568
Go to Haytalk forum. There's a section shown below devoted to repairing NH farm equipment especially rd balers. It written by a member with the handle of Mike10. He's very knowledgeable especially when it's concerning NH equipment.

https://www.haytalk.com/forums/topic/53849-my-nh-repair-procedures-tips-and-tricks/

so you think that the tube the knives are hooked to might not be letting the slide mechanism slide back forward to stop the tying process as it might be seized ?

will try that too thanks

thanks for the help, he seems very knowledgeable

No, the baler does not need to be powered to tie correctly. The cord from the baler is just for an alarm box that tells when the tying operation is starting.
I bought a clean 650 baler this summer. No alarm box with it either. The 650 did the same thing, kept cycling to tie, after the arms had gone to the home position. There is a breakaway on the twine arms, to protect them in case something solid enters the pickup when the arms go down. you can see the breakaway by looking up while laying on the pickup. The 2 halves of the breakaway need to be pushed back together. I use a large pair of channellocks. If you go to Messick's website, search 640 NH baler, section 35 Twine Arm, the halves show as the 2 double L pieces that the #19 grease fitting screws into. I can't seem to get the image to link here. If you tighten the #34 bolt, do so sparingly.
My neighbor's 644 did the same thing this summer. Easy fix, after you know how.

In your first post, you said that you had to cut the twine before you ejected the bale. The knives must be free to pivot to cut the twine. All the linkages that control the auto wrap clutch pawl must be free and lubricated so clutch operation can start and stop. The twine arm breakaway reset can be done by loosening the 3/8 bolt that holds the spring held detent ball, pulling the arms back to home position and tightening the said bolt [don't disturb the jam nut]......Ron