Bumping out of 2nd

71
The guys are pretty much on the money.
I used to repair those parts for a living. But sadly my eyesight wont let me repair the sliders anymore. The clutch teeth on the gears though are still no problem.
Yes, it may be a linkage thing, but only if the external levers on the cover are moving around on their studs, preventing your shift from fully engaging the mesh between the clutch teeth and the sliders. Tight nuts is not the answer here. The levers have to physically fit tightly on the studs.If they move around, they make trouble.I red loc-tite them/problem solved.
Yes it could be a back bearing, but you said recent rebuild.
Yes the struts are supposed to keep the slider engaged.
But once the clutch teeth start kicking the slider back, those struts give up in a big hurry.This problem will only get worse.You might as well drop that baby and get those 6 problematic clutch teeth back-cut now, while the damage is minimal. Do not let your "rebuilder" talk you into new gears. This is a 5 minute fix, with the gear on the table. Have the other gears checked too.Your "rebuilder" should warranty this on account of he missed it. If he doesnt, I'd find a different guy. If you lived closer I'd offer to fix it for nothing.
You gotta fix this ASAP. Theres not that many guys around any more who can fix the sliders. We're all getting older, and either short sighted, half blind or just plain cant see!If you wait too long, you will be buying parts.
So get it over with.Nobody's lying to you here.

That was my point (something has been happening to eventually cause the kicking out).
It could even be as simple as a habit of taking it out of second before the clutch is all the way disengaged, and after time it wears the interlock angles, Oops I meant "synchronizer" angles :D