I have searched for hours on this forum and the rest of the internet, and haven’t come across the problem I am having.

I have a 2004 Polaris Sportsman 600 Twin.

When in H or L, with AWD button switched on, the handlebars will jerk left and right over and over again when the front wheels are engaged and only when the front wheels are engaged with AWD. If I am AWD or not in AWD but just cruising down the road with normal traction in the rear wheels then there is no jerking in the handlebars, and everything is running smooth and straight. It is only when the rear wheels lose traction which causes the front wheel and diff to engage do I experience the jerking handlebars back and forth, over and over until the rear wheels hook up properly and the front disengages.

If put the bike on a stand so all four wheels are off the ground, and put it in AWD, the handlebars jerk like crazy. Youtube Link attached.

The front Sprague cage and main gear was just replaced by the dealer I purchased it from. Both front driveshafts are completely brand new when the cage was replaced. Less than two weeks ago. New fluid of course. Yokes, CV joint and U-joints are all fine and straight.

It did this problem before the cage/gear was replaced, which is why the dealer replaced the cage/gear. It seemed to solve the problem the first week I had it, I have done no aggressive riding or plowing since it was replaced. But now it is back to the jerking handlebars.

Any ideas?

https://youtu.be/iK7WUh9t9lo
Wheels of ground, AWD switched on and engaged of course, and all four wheels spinning freely.

Thank in advance