The ATC 70 definately has an adjustment point. it is opposite of the flywheel. You probably didnt notice it. If you didnt, the cover is probably on it. See if you see a small 2 inch BLACK circular plastic/rubber thing on the side opposite of the flywheel. Where you add oil. That black rubber thing is the cover. It will pop off and then you can adjust it. By the way its a 1/4 turn not a 1/8 turn. You loosen the lock nut and turn the screw to the left until you feel tension. Then you turn the adjusting screw back to the right 1/4 turn. Then with the screwdriver holding the screw in place, tighten the lock nut with an openend boxend wrench. That should get you straightened out.
ClayW
Clay Whitman
Newnan, GA
AMSOIL DEALER
My Toys
2008 Yamaha Rhino 700 SE
1999 Larson 226 SEI 5.0L EFIVolvo I/O LOVE IT