The shift fork in all gearboxes are designed to take a lot of abuse. They have to cradle a gear spinning at high RPM while forcing it into the next position. As the gears have to made of very hard steel, the shift fork must be soft enough not to damage the gear and yet take the abuse. The forks are made of a type of brass and while this insure the gear will not be damaged- the fork can really be ruined in a hurry. If you are rebuilding your gearbox be sure to check for excessive wear of the forks. Note- that keeping pressure on the gearshift lever while the running in any gear will greatly increase fork wear. This means you should always take you hand off the lever in between gear changes.