Hmm I'n not sure about the JTD but on other mk2 puntos the gear selction system st driven by two cables and one rod. One cable is for revese the other for left to right motion and the rod controls gear engagment. I would assume if there is plenty of spring when moving the gear stick left and right then the rod is at fault. There are 3 parts to the rod, the first parts is the bit inside the engine bay wich connects to a second rod whcih connects to the gear selction unit on the gear box. I'd have a look for obvious signs of crossion, exsessive wear so on and so forth. Try a little lubricant on the joints see if this helps. If all seems fine then its possible it could be an internal gearbox fault, but i doubt it very much. Most likly a selection problem.
