After pull starting our small farm tractor the other day in 4lo which i have done plenty of times before it shifted very hard out of 4lo and back into 2wd. I didn't think of anything then but i went to put it in 4lo yesterday to pull it again, it made a grinding noise when I shifted from 2wd to 4lo and even when I went back to 2wd it wanted to grind in and not slide it. It seems like the Tcase is spinning when Im trying to put it in 4lo and back to 2wd. It goes into 4 hi and back just fine but not 4lo. Any suggestions on what it could be before i take it to the dealer?