On old carbs, is it likely that the Thermostatic Spring in the choke has lost some of it's temper? I have spent some time trying to get it to close & open properly without success. I've cleaned the spring & housing, used penitrating oil on the linkage, adjusted it for lean & rich & so on, without success. Basic kits don't include the Spring. And what about the little piston in the housing? Do they tend to go defective? The little heat tube from the intake is connected properly..

Paul