[urq] brake pedal feel

[SpotatAshleys]

Evening All (at least it is here)
I have a strange feel to my brake pedal at the moment. If I describe the symptoms I'd be grateful for a possible diagnosis.

When you press the pedal gently the pedal feels like normal and the brakes work reasonably well. If you stand on the pedal hard the pedal feel is hard with very little braking effect but if you stay on it (maintain the pressure) the full assistance comes in and the brakes suddenly work well. At least at the moment the brakes are stopping me but it is a little disconcerting to say the least. Is this a signal of something starting to fail or can it be to do with adjustment of the rear brakes? I have a problem with these not adjusting properly recently and am trying to work out why but the ground is covered in snow and I don't really want to get under it for the time being (wimp? me? nooo)
Any suggestions gratefully received.

Many thanks

Keith

'87 WR