okay....lol...the early 7's had a different tensioner than the later ones, check the rubber bushing on the tension pulley arm assembly, if they go bad it will throw the belts off, even new ones! You may have to lower the first crankcase guard an inch or so, the one under the radiator to get the belts on the crank pulley.
Thanks rome for the reply... mine is staying on i just dont have any adjustment left and the rubber is old and hard and wont grip pullys any more. My tensioner bushings seemed to be good it is just a pain to get to the 5 holding bolts that have to be loosened before adjusting the top adjusting bolt and didnt know if it was faster to drop belly pan and get to it from the bottom or take the generator off and reach it from the side?