I'll bet it's one if the gear shaft bearings in your internal transmission. I had the same whining noise in one of mine. It got louder until a bearing granades! the trans then locked up! I had no other damage except for the bearing it's self but the tranny wouldn't budge until I cleaned out and replaced the trashed bearing A rebuild kit with sets of bearing are avalible.
In the pic , it will be either # 5,6,7 or 8. Don't bother trying to figure which one, just replaced them all. If one is failing, the others are not far behind. No big deal, they will pop out. they are not pressed.
This is normaly due to poor lubrication, low oil level or poor quality lubricant. In my case, I drained the tranny and forgot to refill
