Well, that points the trouble to Low/Reverse clutch assembly, to fix problem it will require transmission removal and rebuilding the unit as a whole.
Depending on your mechanical skills will dictate if this is something you want or are prepared to do, if you are unsure of rebuilding it yourself, I would reccomend that you contact one of the member/vendors in your area that will steer you in the correct repairs your car requires, you can R&R the transmission and send it to them if you prefer. Check your option decal on inside of trunk lid for trans identification (provided it hasen't been swapped out for different unit),
MV9 is 200c 3 speed, MW9 is 200-4R 4 speed. Information is available for rebuilding it yourself once you ID unit model.
Kevin.