from what i can see in the pics the shaft with the 2 little gears looks very shiny,like its been spinnin in the case cover , there is a washer that goes between that outer gear and the cover, also wondering about the track pitch , should be 2.52... maybe thats a 3....
when you pulled the drive shaft did you undo the speedo bearing and lock collar, and pull it all into the chain case with the bottom bolt and then assemble the speedo side last? wondering also if you ever had the drivers changed?
also looks like the chain retainer ,little bracket near the double gears, could be pushed towards the case a little bit more,kinda close to the chain there.
do you have 4 drivers on the drive shaft or 2 drivers in the middle and a wheel on each end?