Series 3 LT76 S3 gears popping out.

I know this has been discussed before but I’ve struggled to find a thread that addresses the specific conditions in which my gearbox is having trouble.

My vehicle is vin suffix A so assuming gearbox suffix is the same. There is no rebuild tag/plate/stamp on my box so presumably I’m the first person in this box.

Recently I’ve replaced all bushes and bearings in my gearbox and transfer case. Originally my vehicle popped out of all gears under overrun.

I now pop out of 2nd on overrun and 4th under acceleration. Neither gear loss is aggressive and can be easily held in gear by hand.

I noticed some chipped layshaft teeth, stepping on the 3rd/4th synchro hub teeth and the locator pin on the main shaft for my two piece bronze bush was snapped.

I am going to try fitting reverse springs for all selector detents to see if the stiffer spring rating holds my box in gear.

Besides the usual synchro hub springs what would people look at to diagnose the problem? Could it be caused by the issues I didn’t have time to fix the first time I was inside the gearbox? I’m no gearbox expert so it’s entirely plausible I did something incorrectly. (I know I should have replaced the worn items mentioned but as the vehicle is used for work I had to get it out ASAP.)

Thanks in advance

Last year I rebuilt my Series 3 box after it had most of the issues you have.[done series 2a before.]
A major hold up for me was finding decent 3/4 syncro springs, some aftermarket ones are rubbish. Problem solved when a forum member kindly sent me some.
Your problems in the box are likely due to wear/slop in the main shaft train, worn syncro hubs. bearings you replaced so should still be good.

YOU need your box's suffix number. For series 3 it is on the front edge of the transfer box. [ daft I know]
Fitting reverse detent springs all around will not help.
Sorting out shim tolerance's and therefore fore and aft movement in the main shaft train is what on the whole will prevent jumping out of gear as long as gears themselves not badly damaged.
On You tube Steamwally has a very good 3 part series on rebuild of the series 3 box along with some good tips.
Mine is now the nicest series box I have ever used.