The throttle on the 400T won't return by itself. I've taken the carbs off and undone the cables at the carb end - then lubed the cables - they seem ok when not attached to the carbs. When I reassemble the non-return problem remains. Routing seems o.k. The spring on the carbs seems to be quite strong - it takes a fair amount of effort to open the throttle and only gentle pressure to close it. Is a new pair of cables likely to cure this one? John