John Deere LA125 problems! Grinding noise? HELP!

I have a JD LA125 that was new around 12/2008. It just turned 48 hours and I have had zero issues and just recently changed oil and filters. About 3 hours of use after the service the mower is making a horrendous grinding noise! If I push in the brake pedal the noise goes away. As soon as I release it, it starts again. When I engage the PTO I believe the noise is still there but it is really hard to tell for sure because of the extra noise involved. I did a small amount of cutting and it seems to cut fine. I have mainly mowed a flat lawn with minimal hills and no towing otherwise. I've always cared for the mower, used ethanol free gas, etc. I have been doing some searching and read about transmission problems with this unit but I am not sure if this is the culprit. I have a JD dealer not too far away so I can always try to take it in there but hoping to get some insight and maybe fix it myself before taking that step. Thanks in advance for any help!

Chad

There are two idler pulleys on the drive belt that keep tension on it. When you depress the brake pedal, it releases the tension on the belt causing it to stop moving, therefore those two pulleys also stop turning. I'd be willing to bet the bearings in one or both of them have gone bad. But just to be sure, remove the deck and slide under the mower. The drive belt will be on the upper pulley under the engine and will run down inside the frame to the rear where it will then attach to the rear axle. Those two pulleys should be very near the right side floor board. Look for any shiny metal or anything obviously worn, if the belt is rubbing anything, you should be able to see it. Lock the parking to release the belt. You should be able to spin those idlers by hand. If they make any noise or if you can feel some roughness in the bearings, then they need to be replaced.