Problem for 3rd/4th shifting problems found(?) as I dismantled the gearbox for the third time... The 4th gear synchro ring was badly worn on the three slots where the three blocks rest,so much that the bronze on this area had been worn down and the blocks rested on the 4th synchro cone...The synchro ring appeared to have three perfect rectangular "windows" all the way down to its thickness,no sign of damage,breakage etc. That made me think it had been built this way,that's why I ignored it both times I dismantled the gearbox.It must have been working for many kms in such state,in order to make such "machined" wear. Now I am about to reassemble the gearbox but I want to be sure everything is OK.I am putting secondhand synchros on that look excellent,however,does anybody have the height of a new synchro ring in order to determine if there is wear on the faces? The inner cone is OK,is there a way to check this? Are there any other points of wear to check other than the typical ones? (bearings etc)