i'm thinking it can be 1 of 2 other causes then, try this first, on the knuckles you have 2 holes where the pivot balls sit and they have an alloy thread that goes on top of the pivot balls (bottom right in pic in the link below) , tighten these up untill you cant turn the hubs then loosen by a quarter of a turn, or until you can turn the hubs .....has this cured it,
http://www.offroad-cult.org/Tracktes...Monster/P6.JPG
if not check hub bearings are ok