Electric mirrors

Hi all,new to this site.I have a problem with my electric mirrors on my 1997 323i se.When I move the button to move the mirrors I only get a click as if they are trying to move but don't,the click only happens when I try to move the mirrors up or down not sideways,nothing happens that way,funny thing is that both mirrors make the clicking noise when the lever is moved no matter which mirror I try to adjust.I have changed the switch but still the same problem.I checked the power aty the switch and I have power when the ignition is switched on,I thinking maybe it is an earth problem.Any help would be appreciated before I take it do a dealers.

Many thanks.

Paul. :banghead: