Hello,Some gearbox problems can be caused by broken or worn mounts.drive off in first and accelerate hard ,then take your foot of the pedal.if it jumps out of gear it might be the mounts.I would also check the linkage under the coverplate under the back seat.There is also a bush under the gearstick which can wear or even fall off giving you the sloppy stick you describe.Standard gearboxes can be picked up for around £50 .A good workshop manual will give you some idea of the work involved .Good luck.