Long ago I fomulated my own Laws of NonFunctional Mechanical Devices (NMFD). First Law of NFMD is: 90% of all problems are cleaning problems - so try thorough cleaning first. The Second Law is Read the Instructions - covers another 8% - 9% of all malfunctions. Third Law: If 1st and 2d laws don't apply the thing is broke! Find someone who knows what they are doing to fix it (assumes repairs are considerably less than cost of replacement) or buy a replacement.