using my M670 to move lg rd bales on small acreage had 3 lined up flat side to flat side close to each other. The 4th the tractor hunger in reverse and couldn't bump it to neutral so tried to rock it a little by letting clutch out quickly to friction point then back it keeping pressure on shifter. WRONG THING to do. Heard a metallic snap or crack and it went to neutral but now it doesn't move in any gear. PTO works. 3 point works. Looking up in inspection plate to clutch no damage visual and all turns when running. Hoping a key snapped that connect a shaft to a gear on the way to the pinion. Anyone have an idea what I screwed up?? In north Texas looking for Mechanic that knows MM's.