Ok, I have B2150D that I bought new in 1994. Today I went and got firewood in the bucket. I always shift into creep mode so I can get close to where I unload wood, backing out I shift back into midrange,, the transmission would not shift into low gear, but would into second, which it stalled the engine when clutch was release. I started it back up and tryed shifting to low, nothing. Went back to second gear and it lunged forward but was making a horrible noise under the tractor. So I attempted shifting back to low nothing, so I shifted to reverse and it ran fine so i dobe it back to its parking spot in reverse.. any suggestions