I'm just gonna throw this out there because your waiting on help:
But, many of the thumpers have a lever and spring behind the flywheel for the cam chain.
Although, with the ATC70, I'm not sure if it's on that side? I yanked my flywheel to change points and condensor and it doesn't come to my immediate mind that I saw that chain adjust crap??
Which side does the manual say it's on?? Sometimes the locking crap gets bound and you have to lift it with a screwdriver etc etc.
Vealmonkey, blue and the other guys will get you out of trouble.....
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country