One of those irritating little problems! Someone probably will say Aha straight away and give the answer.
Handbrake works smoothly/perfectly and the dashboard light goes on and off OK. However the handbrake lever has developed a little "springiness" at the bottom of its travel so the sensor light may come on when driving and I need to push it down slightly to extinguish the light again.
Shove the front of the car on axle stands and remove the front wheels. Locate the adjuster nuts and locknuts on the ends of the handbrake cables. Now go back inside the car and peering down the hole where the handbrake handle goes, pull the handbrake on and see if the balancer bar is "equal" (at right angles to the handbrake lever) if it isn't, then adjust up (tighten) one side up until it is.
You should find that with the handbrake fully off, the cables go slack and there is then free play in the cable at the caliper end. You want to maintain a smidgen of free play, but as small an amount as possible (or the mechanism in the caliper won't auto adjust properly)
You should find that with the cables adjusted up properly that the equaliser is "balanced", and the handbrake then goes right down to the bottom and is held there by the springs in the caliper levers. You should be able to feel a teeny tiny bit of free play if you hold in the handbrake button, and move it up and down at the bottom of it's travel. There will be noticeable extra resistance as the handbrake cable free play is taken up, and you actually start to pull the levers on the calipers. That movement should be no more than a few mm at the handbrake lever.
Correct. You can have a look at the balancer bar beforehand, and nothing needs to be dismantled at the handbrake end of the cables.
It's actually one of the easiest handbrakes to adjust up I've ever seen. Second only to the X1/9 which uses very similar calipers, but is somewhat more awkward to see the balancer.
My handbrake lever did this when one of the cables needed replacing, the outer cable had cracked open and the inner cable had corroded and started to snag so that it did not pull back properly, and hence did not pull the lever down fully.
But if you remove the front wheels to try and adjust the handbrake you will be able to see if this is the case as you will be able to see the condition of the cable.
Someone probably will say Aha straight away and give the answer. 
