I returned your private message as follows:
The needle frame is the pipe/rod assembly that the needles bolt to. It has 2 flanges on it that the needles attach to. When the needles are off, you can see that these flanges have slotted holes and this is for the adjustment of the needle eye placement when they pass thru the knotter frames. This means laterally and rotationally in order to locate the needle tip in an exact position when the knotter operates.
So, you trip the knotter and slowly roll the flywheel forward to start raising the needle lift arm. Put the needles on the lift arm and thread the bolts in until the needles don't flop around, but don't tighten anything yet. Keep rolling the flywheel until the needle eyes rise up into the knotter frames. They may not even pass thru there yet because they are out of position. But, you can slide each needle around until they do pass thru the knotter frames. By tightening and/or loosening the 2 bolts in the needles, you can also rock the needle eye forwards and backwards as it tries to slide past the knotter frame. The reason they need to lightly touch the side of the knotter frame is to keep them from bouncing around and misthreading the twine disk.
Note than when you load the twine, the needles are 'presenting' the twine to the twine disks and the tucker fingers are then pressing the twine INTO the twine disks. The twine disks then revolve and trap both ends of the future knot.
When you have the needle eyes comfortably passing up over the twine disks, tighten the needle bolts a bit more to snug them up, but don't reef the bolts up yet. You will want to make sure the needle position doesn't need any further tweaking as a result of them being repaired or interferences occuring as they reach the top of their travel. Keep the flywheel slowly rolling some more and see whether the tucker fingers clear them (by a small amount (like 1/8" or the thickness of 2 quarters stacked together). Then make sure the needles retract smoothly without any further contact with anything.
The knotter will end its cycle and reset to the Home position. Trip the knotter again and slowly roll the flywheel until the needles lift, the tucker fingers sweep by the needles and now watch the billhooks turn. At this stage, you need to turn the flywheel VERY slowly, and watch the billhook jaws open (to catch the two twines in the twine disk) and then turn some more to close, Then the wiper arms swing over, cut the twine and wipe the completed knots of the billhook.
At this time you might want to examine the cutoff knives to see if they are sharp. If not, take them off (on the 336 they are bolted on) and file, grind, sand or buy new ones and reattach them. If they are just a little dull, use a belt sander with fine grit to polish them up. The knives should cut the twine, not rip it.
Since you already are experts on the 14T (based on your last message), the exact same process is going on in your 336 !
Just take it slowly, one step at a time. You can even 'play' knotter, by having a friend perform all the knotter operations while you manipulate the materials: Hold one end of a string, bring the other end of the string up into their hands, take your thumb and index finger and twist the two captured ends around, cut the long piece and slide the knot off their fingers.
Being an expert on 1 model baler is kind of rare. Now you will be an expert on two similar but different machines. The mechanisms work EXACTLY the same on JD, NH, MF, Oliver and many others, including round baler models.
You don't need luck for this.
When its working good by hand, tighten the needle bolts 1 flat at a time, alternating between the 2 bolts on each needle until they are VERY tight. Remember that when you tighten or loosen these bolts, you are actually moving the needle tip slightly. So give each bolt just a little bit of tension at a time.
I expect success out of this !!!
