A few weeks ago, my furnace blower got quite loud. So I removed the access panel to see what I could see. The fan blades were caked with dust... so I figured it was just out of balance. Pulled the squirell wheel, and cleaned most of the dust off. This just made it worse. Cleaned it a little more, and now it shakes so much, it sounds like it is banging against the side of the box. Any clue?

I would start by cleaning the blower wheel completely. This may require removing the motor and any other electronics and taking the wheel to the car wash and clean it up really well. If this doesn't help, it sure sounds like you will need a new blower motor. Sounds like the bearings are going out. Also, if you give the wheel a good push by hand and see a large noticeable wobble in the wheel, it may be a good idea to get a new wheel also. Most likely all you will need is a motor if cleaning the wheel doesn't work, but while you are in there, the wheel isn't too much of an extra expense on most units.

Update... Removed a few wires so I could get the fan assembly completely out of the furnace. When I run the fan, it vibrates a little but not too bad. Until I put my hand/arm over the output. The more resistance I give, the more vibes, and louder it gets. There is a little wobble in the wheel, normal end play in the shaft, and slight play perpendicular to the motor. So, I guess my question is... Should I just try a new wheel first, or just go for the motor now too? I Obviously don't want to spend the money on a new motor if I don't need to. It's starting to get chilly in Upstate NY . Thanks

You could start with a new wheel, but while you have the assembly out, I would opt for a new motor too. Also, before doing anything, while you have the blower assembly out, crawl up in the furnace and look up where the blower goes. Can you see straight up through the furnace, or is there a radiator looking contraption (secondary heat exchanger) that is also plugged up with dirt etc. If there is, clean it up good with a wire brush and shop vac. Also, if you have central a/c, your evap coil on top of the furnace is most likely plugged up too and in need of cleaning. Get these all cleaned up and maybe try putting the current blower assembly back in and see what happens.