New Idea 5209 cutterbar alignment with twisted driveshaft

I purchased a well used NI 5209 this year and it works pretty well. I need help with turtle alignment. I have the operators manual, which gives a fairly good discussion of alignment but i do not have the service manual.

First a little background. To begin the season I checked the grease in 2 of the turtles and one was filled correctly the other was a little over full. So I assumed the turtle lubrication was good enough to get going. I changed the transmission oil and went to work. I havent operated a discbine before but am very pleased. I need to master the 90 degree turns or learn to live with sloppy corners or do the stop, lift, back up and turn, lower and proceed method or the lift, turn around 270 degrees, lower and proceed method. But im progressing up the learning curve.

Ive cut about 25 acres so far this year with this mower. Shortly after starting to mow the last 5 acre field I heard a pretty loud metallic clicking so I stopped to check on the mower. I expected a bent knife was hitting the cutterbar. I couldnt find anything wrong. I started to head for the shop but couldnt imagine what I would do, and I really needed to get the hay cut, so I decided to continue mowing. The ticking diminished, as one could expect, and fortunately not wath a metallic crash! When i was finished, i found a piece of heavy fence wire in the area where i first heard the clicking. I had considered that maybe I'd hit some wire but couldn't see any on the ground or in the cutterbar. I did pull a nail out of one of the rollers and wondered if the nail had been hitting the frame. But I really thought the metallic clicking i heard couldnt be made by wire or nail. This morning it is no longer clicking, but did sound a little unusual, like maybe something was rubbing.

So i pulled the turtles and found wire wrapped around 2 of the hubs. One of the turtles had obviously been hit by knives on an adjacent turtle, but the knives on the adjacent turtles didnt have any corresponding damage, so I think the turtle knife impact damage is old. So maybe the wire was causing the clicking i heard. I've found no obvious cause yet, and now there is no clicking.

The cutter bar does have a pretty good amount of compound backlash. It looks to me to be about 45 degrees from the time hub 1 turns until the hat turtle turns (I havent taken that one off yet). So turtle 1 rotates about 45 degrees before the hat turtle begins to move.

I'm assuming the drive shaft is twisted, as normally happens apparently in these NI 5209 mowers but I'd rather not replace the drive shaft if it isnt necessary yet. The operator's manual addresses alignment but doesnt go quite so far as to talk about alignment when a fairly twisted driveshaft is involved.


So a couple of questions for you folks with the same or otherwise similar models.

Question 1: At what point should a twisted driveshaft be replaced? How much twist is acceptable and what is the best way to measure it?

Question 2: Since the hubs can be aligned in 7 degree increments (or whatever the number is) can I manually rotate the pto shaft to get the number 1 hub parallel to the bar assembly and the slack out of all the others like when the bar is cutting, then align the #2 hub (with the slight offset as required), then continue with #3, #4, etc, aligning all the hubs parallel to the bar assembly so that when I install the turtles everything lines up properly? Will I be able to operate the mower like this for some time before eventually needing to replace the cutterbar driveshaft?

Question 3: Is this mower doomed for an immediate driveshaft replacement or is it likely to run for years? I'm cutting a little shy of 100 acres per year of orchard grass.

New Idea 5209 cutterbar alignment with twisted driveshaft