hi there....i wish you put the stairlift model number as to determine straight or curved rail model!!!anyway what you have asked the battery terminals should be from the two wires from the main pcb, black to negative terminal on one battery and the red wire to the positive terminal on other ,finaly then there should be a inline fuse terminal wire connecting the two battery terminals + and -....i will say some years ago on the 300 model the inline fuse used to ark in the holder[batteries] and cause a similar fault to one you are describing where the lift only moves a bit,check this fuse........hope this will help.....ian..portsmouth. uk
IAN, May 2012
