try grainger's website, it's called a unit-bearing motor, just match the speed ( usually 1550 rpm) & watts
( usually 6-15 watts ) & the rotation ( marked on your motors end-cap CW=clockwise CCW=counterclockwise, also note that most motors of this type indicate rotation as viewed from the shaft-end as you look at the fan blades, but some refer to the lead-end as viewed from the rear of the motor were the wire-leads enter it) if you give them the part no. off of you motor, they should be able to cross-reference it. yours says 6-Watts, 1550 RPM, CW you can go a little higher in watts, but not RPM, make SURE of the rotation, (they don't work backwards & you can't just reverse the fan blades either.
http://www.grainger.com/Grainger/unit-bearing-motors/hvac-motors/motors/ecatalog/N-9yd?op=search