hi
not sure if you have the same type as me ( telesteps with round round rubber feet).
if they are the same DO NOT USE WD40 to mantain they .
its nothing to do with slipping off them , its just that they have some plastic insde to stop each section going to high. wd40 melts this plastic stop so if not carefull now they fall apart as i pull them up.
also the feet will wear out very quick , expensive to replace , if you even find a place that sells them. i fitted different feet now set at 75 degrees .
but all said ...still great ladders for the odd use.