Since disassembling, adjusting and assembling the gearbox requires a lot of special tools and since the models described are equipped with three different gearboxes, the work on disassembling the gearbox is not described. We recommend that in case of serious damage, the old gearbox be exchanged for a new one. However, it is important to remember the differences between individual gearboxes in order to install the required one. The models are equipped with the following gearboxes: