hi there.....if you have not used the stairlift in 4 years it will be the 2 x 12v batteries in the carriage,if these are the 2 batteries that you have replaced and you made sure the mains spur switch is on for the supply to the charger, everything should be fine..also check that the footrest plate is not hitting step when down,,,cleaning the rail will not make a differance.....hope this helps......paul...portsmouth u/k
PAUL, September 2013