Will:
More than likely the little leaf switch is defective/dirty/bent that
senses when the door is fully open. Also could be a broken gear or
cam (or faulty timing) that actuates the switch. This is a rather
common problem with the drawers in CD players and DVD players of all
makes and can usually be repaired easily and cheaply unless the
mechanism is forced in any way... then the repair price gets higher
because of more broken parts.
Until you investigate the real reason for the problem I would hold off
on the suggestion of "Give it a thump on the side and try again".
electricitym