I've got a really strange problem with an acorn 120 stairlift. The bateries have just about failed so we fitted new ones only to get an F fault indicated, this has been translated to mean a motor fault but after fully testing the motor its fine.
we put the old batteries back on which only read 11.8v & it works all be it very slow .. we tried a different set of new batteries.. F fault again.
everything else checks out ok. we've put the old batteries back on for now but it barely makes it up.. could it be the pcb? please help.

Mick, March 2013