You r talking about this>> [link=http://www.hpieurope.com/showimage.php?imgSrc=./graphics/walkthroughs/Savage_X_Steel_Spurgear/SX_spur_11.jpg]Spur[/link]
Heres the whole page at the bottom youll see the cluth bell that to may be the problem [link=http://www.hpi-europe.com/walk.php?lang=en&id=14]HPI pics[/link]

You probably need to tighten it.
Pic courtesy of HPI