I had the same problem a while back - - mine locked up in third gear - - it happend at slow speed while driving around the gas pumps.
Long story short - -you will need to pull the unit out and add block stops to prevent this - - TKO told me they only had trouble with their race set-up-I told them I was not racing
but not sure they believed me.
After their fix ( stops ) to prevent over throw - I have not had any more problems.