Turn the T screw CCW until the chain stops turning at idle but not so far that the engine stalls when going to idle. If the screw has no effect on idle speed, investigate the small spring on the throttle arm of the carburetor for damage or disconnect. You may have to clean the trigger assembly of sawdust if nothing else helped. Be sure to make notes when disassembling the mechanism to be able to replace the parts correctly. Hope this helps!
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Turn the T screw CCW until the chain stops turning at idle but not so far that the engine stalls when going to idle. If the screw has no effect on idle speed, investigate the small spring on the throttle arm of the carburetor for damage or disconnect. You may have to clean the trigger assembly of sawdust if nothing else helped. Be sure to make notes when disassembling the mechanism to be able to replace the parts correctly. Hope this helps!