squealing idler pulley?

[footwart23]

i have a new squealing under the hood of my 06 eb explorer. it seems to be the idler pulley because when i look at it i can see a slight shimmy when its running. i looked at my f150 while running and no shimmy.sound like this may be it? would that be covered under the drive train warrenty? any input would be great. thanks

 

[IZwack]

Idler pulleys are fairly simple to replace and they're not that expensive.

 

[footwart23]

serpentine belt was stretched and a bit worn. replaced that and good as new.