Sound likes the runner guides have worn/moved.
dead easy to take out the seats. look under the front of the seat, there should be a small allen headed bolt. Remove this, then slide the seat as far back as it'll go and it'll pop out of the runners.
You will need to refit/replace the guides...ECP / GSF or EBAY,
then, as they say in all the good books, refitting is a reversal of removal.
hope this helps.