At the bottom there's a plastic cover.
Under the cover is a little pull down flap.
Under the flap is a screw hole
Undo the single screw and pull the cover forward
Theres stuff printed inside.
Probably gives the model number
Some places sell reconditioned fans at about half price on an exchange basis. Other people on here say you can oil the bearings to get them going again and or replace the bearings unless the motor windings are broken that is.
Peccavi
February 2009