A friend is riding a 1977 R100/7 to the MOA rally from Missoula Mt. and while riding down the interstate his clutch started to slip. When he pulled over he found that all slack in the cable had disappeared. He then proceeded to adjust the cable at the lever and that did not provide enough slack. He had to adjust the cable at the clutch end to achieve the proper adjustment. He then rode another 600 miles with no problem.
Does anyone know what may have caused this to occur?