4-speed shifter issues

[VonCramp]

I have an A833 18 spline transmission in my '69 Cuda. When I shift into second gear, as the car picks up rpm's if I don't hurry up and shift into third it will buck and kick itself back into neutral... Hard! I think it's just shifter adjustment, but I am not entirely sure. I am using a Mr. Gasket 4-speed shifter from the 70's. I was told this was a heavy duty shifter back then. This is my first Mopar 4-speed, though. Any advice and help would be greatly appreciated. Thanks!

 

[TrailBeast]

The interlocking part of the teeth on second gear are worn out and instead of locking into the gear tighter as more power is applied they are forced apart.

Requires the replacement of the gear itself, the slider ring that the fork moves and inspection of the section of the shaft it rides on.

There is a slight possibility that the shifter is not traveling far enough to allow a full engage of second gear, but a few times of popping out will make it worse fast.

Where it says "here" are the teeth that interlock with the ones inside the ring where it says "and here"
Notice the angles on those little teeth that makes them a pentagon shape?
That's how they interlock under a load, and when those angles get worn they will force the gear out instead of locking it in.

Ever notice how hard it is to take a trans out of gear when it under a load?
Those teeth are why.