Need A833 advice

The trans might have to come apart.
but before you go that far;
Here's my opinion;
Assuming this is a regular A833; and with the cover off, and the forks removed,
I think that there can be only two possible reasons for this situation;
1) there is something pressuring the brass to move onto the brake cone or
2) the brake cone is grabbing the brass and tugging it in.
My money is on the first.
Therefore, here is the diagnostic;
Push the synchro sleeve away from the brass ring as far as it will go. This will cause the struts to pop up, out of the over-shifted slider.
Now rotate the mainshaft, and make sure every strut has popped up. If you find one that has not, figure out the why of it, and fix it.
There is an energizer spring inside the hub that is supposed to apply pressure to those struts. It's just a length of metal-wire, formed into a circle to be a ring, and has a hook on the end. Make sure the hook is indexed into/inside the back of one of the struts, which are hollow to receive it. And all the other struts are sitting on top of the wire. Each strut has a formed edge that is supposed to keep the wire from popping out; make sure that yours are not broken off.
In the car this is a PITA to do.
Once you are confident that the spring is properly so indexed, it's time to pull the slider back over the struts; but first, each strut has to be individually pushed back into the slider. But as you are doing that, the slider has to have a lil pressure applied to it, so it cannot run away; more PITA-uzzury.
Once the slider is centered back in Neutral, repeat your test.
If it does it again, or if you did not find a spring out of place;
then move the slider the other way, and check the Second gear spring and locking edges in the same way. Then repeat the test.

But if you didn't find anything amiss, then it has to be the second reason, and to cure that, the trans will have to come apart, and the brake cone smoothed.
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When I build one of these transmissions, I chuck each gear in a lathe, and polish the brake cones. This is just swiping the spinning cone, two or three times, with a lathe-file that has a length of emery-cloth folded over it.
First I rub off, the step that sometimes forms at the base. Then I just deglaze the rest, and make sure that it is flat. Finally, I put a screw on the face by running the emery from the base to the top and off the edge. The idea here is to bias the cone to grab the brass, as the slider puts pressure on it during the shift process. I bias ALL gears, except first, in the upshift direction, and so the lathe has to be spinning in reverse direction for some of them. I bias First gear for downshifting, but not aggressively, because it makes it too difficult to in-shift when stopped.
Now, if Passon did the same, but in the wrong direction, or more aggressively............ it doesn't take much pressure for the brass to climb the screw and grab it ........... My own A833 shifts like lightning.

But again; My money is on a spring pressuring the brass, which might just be out of place, or one of the struts is damaged.

Good luck