hey fellahs, such a thing as a quick diagnosis?

I recently resurrected a 73 CR250. We used to have 2 of them in the 70's. One was left at a farm for years, where a bunch of kids rode it until they broke it. I didn't know what the problem was. But after getting the farm motor running well, (the other motor is seized badly)
I ended up getting it out for a ride. Everything seems to work except, it falls out of gear, when the power isn't applied...and is very difficult to locate neutral at any time.
The shifter just doesn't seem to have that 'positive' feel.
All the gears work, but say, if you are on a trail, and get off the throttle, you will go to hit it again, and the bike is in some kind of neutral state, another bump of the shifter either way, (with the clutch in) will get it into gear. I can take the other motor apart, and use it to replace whatever is broken....what do you think might cause this?
a breakage? or something like a 'bent shift fork', as they say. Any takers on this? Thanks alot.

Probably the shift linkage tension spring (case side) doesn't match up with the centering pin (clutch cover side). check that (also see exploded parts diagram on this site)

thanks, leftcoast

when you say clutch side. it's pretty obvious which side you are talking about. when you say 'case side' that kind of means, the other side obviously. why is this referred to as the 'case side'? is this the side that most of the tranny stuff stays in when you split the case?
for the record...I am a big auto and bike enthusiast, with lots of mechanical experience, but I've never split a bike case before....and am rather hesitant, although I know I have to do this to replace the part, or realign the pieces you mentioned.
Should I try to leave the 'case side' down, as I pull the clutch side of the case up and off? it gets to this point, and I am working blind.
although I do have the diagrams and parts list to work from.
and a good parts engine with a good tranny. any tips please sir?
thanks alot...I think I see what you are saying...shifter shaft would be out of alignment with gears.....won't centre itself back properly, after pushing one of the shifter plate things. maybe some kind of a pin aligns these things and holds them together?