Any one of you who's ever had the misfortune of working on a Carrier, Bryant or Trane furnace with one of these inducer motors knows what a sweet old Bill these can be. The price installed is north of a grand (over $1000) and before they fail they can sound like the power steering pump on your old Dodge. This is enough to drive any homeowner crazy, but the price will be more than that for them to drive you out of their home.
If you've had to suffer through reading my fine posts, you know full well my opinion of these little darlings. I recommend replacing the furnace if it's a Carrier or Bryant, or at least upgrading the works if it's a Trane. ECM motors for an inducer assembly are great in theory, but from a durability standpoint they miss the mark. Okay, so you want an alternative to kicking yourself and spending hundreds of dollars. I have a crazy 21st century fix that just might work. Really, this qualifies as a redneck repair. However, it might quiet this motor down and could even prolong its life. As long as you're careful, the repair will cost you nothing.
The picture may or may not look exactly like the one you're dealing with, but the rectangular housing on them is all the same. This is what you need to concern yourself. As always, I have no control over your work and the risk is breaking an expensive part and having a no heat. The little circle in the center of the unit is the fan for the whole works. There are fins that draw away heat from the circuit board that lives underneath. G.E., in all their reasoning forgot to include some kind of spacer behind this fan and it can walk on the shaft into one of the I.C. (integrated circuit) chips behind it. This plastic rubbing against the silicon (not silicone) could be what's making the noise as long as the bearings are still intact.
To fix this you're going to need to pack your patience, a small Phillip's head screwdriver, a pry tool, and possibly a plastic fork with one of the inside tines removed. That pry tool can be a small flat head screwdriver or butter knife and the plastic fork can be your hand, but no metal fork should be used. Use the Phillip's screwdriver to remove the two screws and the pry tool to unclip that plastic cover. Take your time in getting this off so you don't break it. Once this is off, you'll see a circuit board and the little plastic fan. Gently rotate the fan with your fingers and if there's any resistance, check what it's rubbing against. If it's rubbing against any part of the board behind it, you can proceed. If not, you need to replace the assembly. You can pull the fan forward with your fingers to free it up, or use your fork to do the same. Do not pry against the board and if the fan gets bent in any way, you'll have to remove it and straighten it out so it's flat. Either way, make sure it clears the board and when you reinstall the cover, well the cover. Turn the fan with your finger to confirm this. As long as your satisfied with your work, turn on the furnace and it should be as quiet a church mouse. If not, either the motor is screwed or you didn't get the fan on right. The fins need to face the front and not the board. Maranatha!