One more picture. After I pulled the kick idler gear I found some interesting marks around the bearing. I 
did a good job of cleaning the case screws and yes, they have been removed at some point, Probably
when this bearing failed. I also notice I have a bit of end play in the clutch shaft. No much, but a few thou. 

Going back a page it looks like you have the flat bearing reversed & that thin washer should be behind to save the rollers from the cast steel center. Then it looks like the big thicker washer 'of shaft size' is missing & should sit against the spacer & it all bolts up tight with the rollers baring against 'that' thick washer. That would account for you gap behind the nut.

Yes i see the other shaft bearing & punch marks but won't comment as that's for later if a problem, maybe tap it back case flush & hope it stays there. They're pretty hard on the case where that bearing fits if they kick back or damage a flywheel key or even start backwards & then lock up. All the problems started with light flywheels & reed valve on these. Unheard of issues with CT1's. We repaired-replaced untold cases t work as we sold them as farm bikes & sure enough any weakness the farmers will exploit those faults. Factory was scrambling for a cure but then bought out the placid AG175 with heavy flywheel & permanently open decomp hole to soften it up to a good farm motor. Sorry that's everything 'But what' you needed to know. Best of luck.

I was referring to thick-ish washer on the left in post #11. Just a note--i see the fiber clutch plate visible looks a bit glazed or burnt. Does it slip at all.
Also looking at the pic of everything i don't see the chatter dampening rubber ring that sits between the clutch basket & big gear. It slots down in & damps any basket movement for & aft which gives a rough chattery idle if it'll idle slow enough. Not a compulsory item but good addition. Think it was shown in a link or pic one of us put up. Shown siting behind the big gear in the drawing but stretches over & in the gap.

The flat bearing and washer aren't laying like they came out of the bike. The bearing was riding on
the cast hub of the outer basket and the washer was protecting inner basket from the bearing riding
on it. I just had them laying wrong when I took the pic. I ordered the bearing and washer and the other
washer that is shown in the diagram along with the o-ring. I pushed the idler gear bearing back in the 
case and  did a little more, ah, punch repair to retain it in the case. I am anxious to get the parts to 
see how the 174-16154-00 washer works. I thought that it was odd that the bearing was riding on
the clutch hub. I also went ahead and got some friction discs for it. They were measuring about 25mm 
undersize. This has been a good discussion and I thank you for your input. I am 72 years old and
worked as a mechanic most of my working life. Been into a lot of transmissions over the years, and 
the play behind that nut just didn't "feel" right. I will let you know how this all works out when I get the
parts. BTW, I don't know if the clutch had any slippage or not. The worm gear was in dire need of
replacement when I got it, and it not run for quite a while. D

Ya doing good young man--I'm a few years older haha. Look forward to the update when parts arrive. Clutch wear isn't really the issue but more how cooked the plates get & just plain give up gripping as they should.

Agreed. I am hoping that all the internal parts are in there and in the right order.
I really don't want to split the cases unless I absolutely have to.

Meant to add something last night but forgot. With the output shaft bearing wandering out i wonder it there's room to make a plate similar to the mainshaft one to retain it. Case is likely not dead parallel in the hole now so bearing is encouraged to move sideways. I think yamaha mucked up a bit as the final drive bearing isn't retained over behind the sprocket. So nothing except tight fit to stop the lot moving over when the small bearing moves as yours has. Even un-bending the sprocket nut lock tap with screwdriver & hammer could move it all. If i 'had to' i'd be tempted to run a good quality thin but big od washer between circlip 22 & the case just to keep 22circlip off the bearing. Maybe not the best idea though. & with the flat bearing, it's got to be running between washers one way or the other & not cast steel--but i know ya onto that. Give that shaft a friendly tap & see if it moves over but hope not. Sorry i'm woffling, nothing better to do lol.

I may have a tranny shim washer that might fit behind the kick idler gear to help retain that brg. I have to move some bikes to get behind the table to tap on the sprocket shaft to see where it goes. And on the flat brg, I thought it was odd that there wasn't a washer on each side of it. BTW, where do you live?
Looked at the diagram and you are talking inside the case. If I have to get that deep, I'll have a look. Doubt this one will be ridden that hard anymore, at least by me.

I'm in NZ down under so not much use except trawling my memory from days gone by. I'm sure if anyone can come up with a plan or cure you'll be able to do it. Bearing needs to be retained by a circlip & was destined to be a problem from the start. Another thing i'll just gloss over is if they derail a chain & it bunches up around the front sprocket it can break off the end of the selector drum under the three screw plastic cover above the sprocket. Hope it doesn't do that but will be obvious.

So the chain breaking business… was that only related to “old” Yamaha factory chains?
Sneezles61