66. At the first sign of failure in the operation of the box, check the level of transmission fluid, as indicated above.
67. If fault is related to full throttle downshift or gear selection, check downshift cable adjustment and gear selection mechanism.
68. If the problem is that the engine speed changes when shifting from third gear to fourth and vice versa, you can try to adjust the brake band.
69. Further troubleshooting should be entrusted to a specialist.