Old Polaris Tech (or anyone else that can help me),

I've finally decided to fix the growling noise in my 2005 Sportsman 500 transmission after putting up with it for 1 year. Unfortunately, I can't seem to find anything obviously wrong and need some help to find the noise. Here's what I've done so far:

1.) Took off the front drive shaft. The growling noise continued, so I ruled out bad u-joints, front differential,...

2.) Took off both rear hubs, and inspected the bearings. They appear to be a little wore, but not that bad. The bearings rotate smoothly and I can't feel any rough spots that would cause a growling noise at high speed.

3.) Pulled the transmission, and split the case. Again, I can't see anything obviously wrong. The chain tensioner, pins, and spring were disassembled, but I think that happened when I split the case. None of the gears look bad and/or worn. I checked all of the 5 bearings that are visible, and none of them appear to be bad. When I rotate the trans by hand, I can hear a slight growl, but can't pinpoint where its coming from.

Any help and guidance finding this growl would be appreciated by anyone.

Thank you