Gas and Oil Home Heating Furnaces - Blower not running

I apologize if this has been asked before but I'm having a problem with the blower fan in my furnace.

Our blower fan was making a loud chirping sound, so I took it out to check the belt and clean it. I found that the belt was cracked so I replaced it. I've cleaned everything. Now, sometimes, the motor will start, but it won't turn the belt. The belt is a 4L360 and the only difference I can see between the new belt and the old one is that the new one has a 15 on it and the old one has a 34. I have no idea what these numbers mean, or if they are even relevant since both belts are 4L360. I've tried loosening and tightening the motor to adjust the tension of the belt, but that doesn't seem to be working.
Also, when it does occasionally run, it's very loud. Almost like it's working overtime to turn the belt.

Any suggestions or insight would be most appreciated.

Thanks!!

What does it do when it starts? Does the motor and its pulley just spin and the belt and blower don't turn? Or does the motor sometimes not start? The loudness could be that the blower is out of balance or something could be in it. Like a dead mouse or something.

Thanks for replying Mattison.

The motor starts and tries to turn the pulley, but after a few seconds of not turning it, it shuts off.
I don't think there's anything in it as I had taken it out and cleaned everything and didn't see anything. The only thing I changed was the belt.

After the past few days, the temperature and the humidity have gotten ridiculous, so we ended up calling a technician to come look at it today. Hopefully it will be something covered by our home warranty.

When was the last time you oiled the blower motor?
With out the belt on will the motor run???? Can you spin the blower wheel by had with the belt off??

ED ;)