Not sure which conversion you have so this may not work, but on my 90, it's pretty simple - go to the front of the seat and put your hands under the bench part of the seat and grab the iron bar in the front (next to your legs). Pull up and toward you. You may need to have a friend work the back side if the springs are still in good shape - they'll push down on the top of the back of the seat. The seat bench area will move toward you and the back area will lay down.
Good luck! | 
