Allen's answer at the foot of this thread was spot on.
I've noticed that the batteries do not sit snuggly in their compartments - they rattle about - so the electrical connections to the internal circuitry is sometimes a bit flaky (e.g. a dim display or a broken connection to the wireless receiver). To get a tight connection:
- take the batteries out
- get some aluminium foil and fold it to fit into the bottom of battery compartment (on top of, and across the width of the little metal plate connector that the batteries normally touch).
- reinsert the batteries
- still loose? make the aluminium wedge a bit thicker
This is also a good solution if your bottom connector plate has been affected by leaking batteries. (Corroded metal is a poor electrical conductor.)
I use this technique in the kids' toys' battery compartments as well when they haven't touched them for ages and the batteries have leaked. Saved me a fortune when a Lego Robotics control unit when snafu.
The Kernel
October 2012