Not sure exatly about a Cav, but these seats are pretty generic.
Look 'neath the seat for the track, which will have "teeth" on it.
then look for the "pawl" which locks into those "teeth".
Pawl is stuck in teeth. Good luck, Pawl!
The release lever (The plastic thing you move w. your fingers)
ain't lettin' poor Pawl outa those teeth!
Pry pawl loose (GENTLY) and apply copious WD-40.
If the lever is snapped, off to the parts counter.....
Jim in Quincy MA, August 2006
