RX75 has been running fine. This morning, I start to mow the yard. After about 15 mins, I stop and put it in neutral w/ engine running. Go to put it in gear and it won't move. Rock it back and forth, shift to Reverse, pump the brake and clutch, engage and disengage the mower deck, and nothing. Then, I put it in 7th speed and it takes off. I stop and try to put it back in 1st or 2nd speed and it won't move. Put it back in 7th and it won't move. Then suddenly I hear a screech and this smoke starts to come from under the engine. The engine seems to be running fine, so I'm assuming it's a clutch or transmission. Any suggestions?