Well despite cleaning the holder, replacing the fuse and charging the battery my unit would not power on.
I couldn't get any output from the battery using a multimeter so figured the immediate problem was there.
Took the battery base off and found the wire to the fuse holder had desoldered and was disconnected. Tried to take the fuse out again and the holder crumbled away. Logic tells me that this has been subjected to some pretty significant heat during use.
I've got power within the battery checking it at the main feeds so once the fuse holder is sorted I'm sure it will work again.
The concern is why it is blowing in the first place. Replacing fuses each ride is only masking the issue, there must be a root cause for the problem. Is it that I'm just expecting too much from this system. I'm north of 19st and the ride home is a sustained uphill slog of about 300ft over 2 miles. I try to keep the cadence at a decent pace and yesterday mostly managed to keep the C961 battery indicator from flashing empty.
I don't want to just blow fuse after fuse if damage is being caused elsewhere.
Where should I be looking (apart from weightwatchers!)