Going on what I've read and heard, a cable between the power electronics and the motor, or within the motor itself appears to have broken - it won't drive at all. (it's not stalled, where would would send a large current with no rotation).

The problem is, the wheel is HUGELY geared down, I can't remember the exact figure, but as a result it's very hard to 'turn' the wheel just by dragging it.

This is unlike the previous trouble with the same wheel in the Sol 150-350 period. Then, the motor was turning when commanded, but drawing more current to do so due to an increase in friction within the gears. They decided to 'save' what was left of the wheel, and drove backwards, commanding a rotation of that wheel approx 10% of the driving time, thus one saw essentially a punctuated trench

(drag, turn, drag, turn)

Now, however, it wont turn at all. So they just drag it along, thus it digs a big long continuous trench.

It's hard if not impossible to say if the high friction of 150-350 is related to the current failure. It's worth noting that the friction of that wheel had actually returned to nominal, the assumption being that grease was re-distributed within the gearing by driving it backwards. As a result of that experience, both rovers drive both forwards and backwards as a matter of course, whereas before they tended to do longer drives facing forward.

Doug