Disassembly of the mainshaft is straight forward, with the center support and rear bearing removed first gear slides off and under it is a snap ring that holds the 1-2 slider on. The pick points to the groove it goes into. My understanding is this snap ring has been discontinued and is no longer avalible so be careful with it. Once the snap ring is off second gear and the hub and slider can be removed. The opposite end of the shaft has another snap ring and it holds third gear and the 3-4 slider the same

Although the trans can be rebuilt without removing the cluster, it cant be done right. The cluster pin removes from front to rear and this is what you will find times two. This shows two sets of needle bearings, there are four total. carefuly check the pin for pits. it is the inner race for the bearings. Each end of the cluster should be smooth with no grooves where the thrust washer rides.

As you can see the teeth on this gear are not in very good shape. The pointed end is broken off on lots of the teeth. What is left is worn at an angle that helps it to pop out of gear. This gear was replaced. You can see better how the syncro sets on the cone of the gear. It should set nice and square on the cone also. I have seen both new and used syncros that rock back and forth on the cone and they dont work very well.

This is first gear sorry its so blurry, it has the syncro setting on top of it. Because of the taper involved with the syncro and cone on the gear it sets with a gap between the gear and syncro. The smaller this gap the more worn the syncro is. All of the syncros looked reall good in this tranny, I suspect someone threw a kit with bearings and syncros at this tranny and never looked at a bunch of the hard parts for it. The teeth that lock into the hub are in good shape they havea nice straight edge with a nice point on them 

This is the mainshaft and its gears, to the right is first gear and it with its syncro will slide off. Under fist is a snap ring that holds the 1-2 hub and slider on, be careful with that snap ring I believe it to be no longer available. Most of the time holding the hub and slider together and droping the mainshaft  carefully on the splined end will drive the hub off. The other option is a press. Second gear will come off with the hub an slider. Similar procedure for third gear.  

 

Thought about the same thing. Sounds like a goo way to launch the ball through my tin roof if not carfefull.