How to clear E3 error code on Vitesse Evolution treadmill?

Hi
I have a Vitesse Evolution treadmill, approx 6 years old but wasn't used much initially. Have just had control board fixed after a fault. Now, I ran it for a few minutes and the belt was sluggish, then surged then stopped with error code E3. Have taken off hood and can't see anything immediately wrong with it but don't know how to get rid of error code. Tried reset, did nothing. Can't find any information for this make of treadmill so any help appreciated!