XDJ-R1 - Tempo sliders malfunctioning on left deck

Hi, I've noticed a problem on my XDJ-R1 over the last few days on the left hand deck. The tempo slider on this side does not go up all the way to +6/10/16. The right deck works as expected and when moving the slider up on the left deck (to decrease tempo) that also works fine, but when set to +/-10% I'm only able to increase tempo on the left deck to approx +8.5/9. The number varies but never reaches +10. This also causes problems with mixing - the tempo seems to jump slightly when playing a tune sped up on the left deck and constantly needs to be adjusted.

I've tried resetting to factory settings (through the ERASE function) and am on the latest firmware. The slider itself seems in fine condition so it appears to me as if it is an issue with the firmware, although am no expert. Any help on how to fix this much appreciated.