Not trying to incite you. The only way two unintended gears can engage is if they move out of position while other gears are engaged/engaging. The circlips are the culprit. After the damage is done, the gears bang the clips back into the groove. The side load on the shift forks is not enough to get them bent prior to the gear damage, but the gears damage may bend the forks in the process of getting chewed up. So, the solution to prevent future mayhem, new gears and shift forks. You can go back to stock circlips, but it just gets you back to the point you were prior to the grinding. Improving on the strength of the circlips/groove is insurance they will more likely stay where they are intended to be. You can send the new gears you have bought to Robinson and they will use them for the rebuild. I understand it’s an international shipment for you, but I can say my transmission is noticeably smoother and definitely stronger than before. Picture included to show you where I have been. My improvements involved the improved billet 4th gear, wider/stronger clips/grooves, and back cut teeth on the gear dogs. My total cost with Robinson’s work and my new shift forks and gaskets for the repair was under $800. 2nd option mentioned before, find a local drag racing motorcycle transmission shop. They will know about back cutting dogs and how to strengthen the system