DDJ SX2 Right Tempo Changer Not working

So suddenly 1 day the right pitch changer on my ddj sx2 decided to break, so it moves fine increasing tempo past the half way mark, then as soon as so start going the other way nothing will happen till a certain point where it jumps from say 125 to 117 in the smallest movement of the tempo adjuster, making it almost imposable to match the BPM, please how can I fix this cause its killing me i have tried re installing Serato and updating the firmware, everything else on the controller is working as it did.  

Just tried using a midi monitor, basically it records the change as normal then as you decrease to that certain point theres not much change then suddenly lots of events, indicating why on serato the pitch doesn't really decrease then in a tiny space does loads, what can I do with this? does it mean my unit has broke