P38 central locking problem

My 97 2.5 DSE central locking has never worked since the day I purchased it. The key fob buttons do "slightly" move the catches but not enough to lock/unlock it. It does however set the alarm when the lock button is pressed.

it also reads "key fob battery low" each time I turn it on/off

is it likely to be a simple case of the battery in the fob is low or is something likely to be seized and not moving the locking mechanism?
I'm guessing its more likely to be the latter and if so what can cause it? As it would be nice to lock her up once in a while

Matt

Duff door locks if they try to move but new batteries in the FOB would not hurt. If the door lock motors are burnt out, it will be the RF receiver in the car at fault.