Ernie, I had a very similar thing happen to mine, but the problem was with the spiral groove cut in the carb barrel. The idle stop screw had worn though the anodizing and was galling. I cleaned the burrs off the stop-screw and groove and all is well... well, no it's not because I yanked the carb off and am using a Super Tigre carb so I don't know how much longer my "fix" would have worked.

(An aluminum carb barrel? Why in the world?)

Anyway, hope this helps,

-Joe