Tremec 3550 Stuck in 3rd

[Fivepoint383]

I got home from the track last night and on the way home I down shifted into 3rd and it is now stuck in 3rd...I have the stock shifter on it and a King cobra clutch. Any Ideas as to what it may be?

 

[EMW150]

My Tremec has done this to me about 3 times now although mine's usually 2nd gear. It's a pretty easy fix. I can unstick mine through the fill plug with a screwdriver. The shift lugs get out of alignment and then it locks. You gotta get in there and push it forward to align with the others. If you can't do it through the fill plug, you can access through the cover on the top. I don't know what causes it but it's a pain in the ass.