My furnace blower won't stop running can you please tell me what the problem may be?

Two months ago I noticed furnace blower would switch off after being on a couple of minutes. Once I heard some humming, thought it was the motor. Had a techinician diagnose it, he said it was the blower motor, a $400 repair. I pulled it out myself, took it to a electric motor shop. They put...

A friend asked help about his furnace blower emitting a screeching sound during operation and then just stopped. I went over and tried to rotate the blower by hand - resistance to free rotation was present. Removed the blower assembly and dismantled motor. No lubrication on both motor bushings....

This morning my furnace in the attic was making some weird sounds. By lunch time the was a burning smell through my vents. At lunch time no heat was blowing through my vents in the house. I turned the a/c on and still nothing. My unit outside is working fine too. What do you think it could be?

Been searching but so far I haven't found any information that really helps me. I've lived in this house for about a year and a half now, it has the original furance in it(house was built in the 70's I blelieve). Last year the furnace worked fine, and had worked fine so far this year. I live in...