Slight grinding noise behind the instrument cluster
 

Hi all,

I have an 04 Escalade that I bought in 05 with 1500 miles on it and I have always heard this small grinding sound behind the dash on the drivers side. I almost sounds like an old electric analog clock. It a very low sound and not really audible accept when idling in park but is there while driving also. I took it to the dealer once and they replaced the whole instrument cluster and the sound went away for about a month but came back.

Anyone else have this? Any ideas on what it could be?