DRT Gear Flame51mm  Gear Selector , Race Proven Parts
Gears jumping out are a sure sign of a worn shifting claw.
This should be replaced as soon as possible in order to avoid a defect of further transmission parts. When disassembling, also inspect the tooth flanks of the transmission gears. If these show pitting marks, they should be replaced. The following types of shifting claws are available:

three-speed gearbox: The three-speed claw is easiest to identify by its only four existing detent points (three gears + neutral). The very early 3-speed transmissions (up to chassis no. 15325) also have only two arms instead of four.

four-speed transmission: There are two different designs. These can be quickly distinguished in the area of the pins that engage in the gearwheel