I would follow Spadges advice first as ratchet problems can occur quite often,id be very suprised if it was anything major as ive never had a minutes trouble with the car since i fitted the new clutch.If you do have to take the box out and you can get access to a ramp your looking at about 3-4 hours work not particularly hard,i changed the sump when i took it off and took all the steering gear off and the engine out and drove home in it that night.