anyone know what error code F -18 on a hotpoint means ?

No communication between circuit boards
Possibly a duff connection on one of the board connectors. Power off, remove covers, disconnect circuit board connectors and clean with toothbrush. May help to tighten them with a pair of pliers. Clean off any corrosion or crud, refit and test.
failing that, its a replacement motor circuit board.
Check out my site for info: www.2ndwave.co.uk/manual.html

dan
February 2008