Lennox Furnace Fails at -31.5C

We woke up this morning with the temperature in the house at a cool 10C. After starting the fireplace and checking the exterior vents I checked the lousy (high efficiency ?) Lennox exhaust fan. The motor was seized up. This is the 2nd motor that has failed on that 12 year old furnace. Not a good record.So I took the motor off, sprayed it with WD-40 till it was completely soaked. Since the motor is welded to the fan assembly it was hard to get the oil to the 5 cent bearing. (Big print on the housing - "DO NOT REPAIR OR RE-USE) Eventually I got it working squeakily. By the time we left for church the motor over heated again.After church I will see if Home Depot carries replacement fans. If not I'll have to cut the fan housing so I can repair AND re-use it.