I know this is an old thread, but hey, it's relevant to my situation.
Anyway, I seem to have a similar issue with my control box, I only ever have one green LED. I drove it all the way to Cambridge (about 5 miles) without any increase in "use." Cambridgeshire is flat...but surely not *that* flat. I just wondered if anyone else has a similar issues and wether the only fix is a new ULA...
(Unfortunately I didn't get it all the way home as my axle snapped... I've got another on the way though!)
I'll get the control box apart and inspect its contents, it's possible there's something amiss in there... Otherwise I'll have a look at making a ULA replacement...
It does at least drive as it is though (minus the current axle issue) so I'll make sure to be careful with using the motor too much, looking around here it seems that there's a possible issue of melting the glue holding the magnets in the casing, so as a temporary solution I should probably get a thermometer!