Stannah (old) stop sensor not working?

hi there......all stairlifts have limit switches fitted to them......1/ slowing switch 2/stop swith 3/ ultermate switch, which only comes in when lift over travels top/bottom and turns everthing off at the same time..then wind lift back slightley and comes back on again...most of these limit switches our replacable, but i am having trouble reconising your stairlift [white wheel lifted!!] i do not think this is a stannah as most old stannah stairlifts had limit arms on back of carriage[wall side] and would hit a rail peg top/bottom to slow/stop lift.......is this stairlift a curved rail or a straight rail model and give a colour if possible....ian...portsmouth uk

IAN
November 2011