1987 AXOD Trans Problem

i have 1987 mercury sable that won't shift out of first gear. so i changed the speed sensor. but no help. so i took the top off the speed sensor cover and pulled out the shaft that goes into the trans. the gear at the bottom of the shaft. locked into another gear. that gear had slid over far enough that the shaft would not engage. Is there a clip that hold's that gear in place? Please help!!!

if you end up needing a new trans. im selling my 88 sable as a parts car it has a strong trans. and the 400 bucks im asking for it is a lot better than a 1000 for just a new trans.3.8l v6-134,000miles