Yes! very important to pull that magnetic screen to see what if anything is on it! That should be a first step before going any further!
The following are several questions I might be asking if I was there in person or things I might try myself.
I did a quick look back in this thread and may have missed it but can you say if this is a new problem? Or is this a new machine to you and it has done this from the first time you touched it?
If this machine had been working fine without this noise how did it first appear?
Did it slowly get worse or was it working nice and smooth then out of nowhere it started making this jerk/noise?
Same operator and job or new guy who never ran a machine before?
Does it seem nice and smooth when driving along down the road and only time it makes the jerk/noise is when stopping and starting or changing directions?
How about if say you are driving in 1st gear and shift to 2nd then to 3rd? Does it shift smooth from one to the next?
While drive shafts were out did anyone try turning the yokes to the front and rear axles to see if they had about the same free play/back lash?
How about with wheels blocked and parking brake released, did anyone try working the output shaft back and forth to feel free play in transmission gears?
Not saying any one of these questions will give a positive answer to the problem but might help eliminate something or raise another question.
One more thing does anyone else think this machine sound like it is idling fast? Hard to tell listening to the videos. Does it have a tachometer? Just checked SIS and it should have one. So what RPM is it running at at low idle?
One more thing I looked in a trouble shooting chart and found reference to Jerky shifting:
Problem: Clutch engagement is sudden. (This symptom causes jerky shifting.)
Probable causes:
1. Modulating valves (5) , (6) , (7) , (8) , (9) , (10) need to be calibrated. ReferenceFor additional information about calibrating the modulating valves, refer to Testing and Adjusting, "Calibration and Programming".
ReferenceFor additional information about calibrating the modulating valves, refer to Testing and Adjusting, "Fill Time for the Transmission Clutch - Calibrate".
2. Modulating valves are unstable.
3. A speed sensor has malfunctioned.