problems with my heated mirrors

Hi,

I've got the following problem with my heated mirrors on my 2000 A4.
Sometimes they work and sometimes they don't work. the elektronic adjusting
always works.

I always put my drivers side mirror closed because of the traffic where i
live. and sometimes when they don't work, i jiggle a little bit with the
mirror and than it does work.

could this be a fautly contact or has enyone else had this problem?

thanks for replying in advanced.