ATVConnection.com ATV Enthusiast Community - Grizzly 660 Transmission Noise

I have a 06 Grizzly 660 that I just love and have what might be a big problem. I was up in the mountains in the snow a couple of months ago with my son. Took a break to eat lunch and my son wanted to take my Grizzly out for a run through the snow. At this time of day the snow was getting pretty wet and it was getting more difficult getting through some of the thick areas on the trails. As I was sitting there my son got stuck. He put it in reverse and started to back out and only got a couple of feet. He decided that he was going to go forward and back until he could get out of the situation he was in. Well he got to quick on the shifting and shifted while the RPM's were too high. He told me that he heard some grinding and such. I checked out the shifting later on and everything seemed okay.

Well on my next ride I start to hear some type of whining/loose noise coming from the motor. I think at first it is the brakes or something but put that theory away once I looked at it closer. The noise is not that loud but enough to be annoying. The noise also comes and goes and is usually only heard at lower speeds, mainly around idle. I checked the belt and everything and I'm pretty sure it is coming from the motor/transmission section. I have since taken it on a couple of rides but I'm thinking it is about time to brake-down the lower end of the motor to see what is going on.

Has anyone else had any transmission issues or experience that might guide me (besides not letting my son ride my quad anymore!)? Don't have much experience on small motors but think this is going to cost some money to get fixed. Any thoughts or advice would be helpful.
Thanks