While you wait for answers, we may have found some information which could help you.
Click here for Challenge Extreme Modelwhere do I get 18v battery for Challenge Strimmer DCSRT18?
Blade guard?
where can i purchase a spool & line complete ?
Spring for Prop Shaft in a 250W Grass Trimmer?
spare part for challenge extreme?
what is the sparkplug gap setting?