Loud ratchet noise when turning printer on....I... (by 2 users)

The problem is a broken gear. Part number LJ7416001.
It is in the fuser assembly.
To remove:
Looking at the back of the laser, you will see a flat "platform" going across under flipdown access door. There is a screw in the middle of it. Remove it with a philips screwdriver, and slide the plastic platform out.
pull the door downward to about a 45 degree angle or so, and it will slide off a pair of flat retaining pins. One on each side. These are part of a molded plastic piece. Each piece is held on by two screws. Remove those. The plastic pieces come out:
NOTE: there is a hook on the bottom of each piece that hooks into the metal frame. The hook faces down. DON"T break them off. The plastic needs to move up and out. After removing the two pieces of plastic, you will see a metal enclosure on the right side of the printer, with two phone jacks in it. It is held on with 2 screws. Remove them and swing it out of the way. Behind it is another large philips screw. Remove that. On the other end of the fuser is another screw. This one has a slot in it, and a small cross slot. Use a flatblade screwdriver to remove this screw.
After it is removed, you can slide the fuser back. you will notice that there is a small multiple wire cable on the right. Unplug it.
On the left are two leads that feed the heater. they plug into a connector that is in the left side of the printer. Pull the connector out, and you will see on the top or bottom side of the connector, a clip that holds these together. Press it toward the connector and pull it apart.

Remove the fuser unit.
With the red roller downward, you should be looking at the top of the fuser. The white power leads run along it. At each end of the fuser, there is a philips screw. One of them will be kind of hidden by the white wires. Remove those two screws. DO NOT REMOVE the screws holding the small pieces of metal under the wires.
After than turn the fuser around so you are looking at the paper rollers and the blue levers.
Just to the left of the left lever, and up about 1/2 inch, you will see a plastic "latch" that hooks over a ledge. CAREFULLY pry it back, and press up on the top of the fuser. On the other end of the fuser, there is a small black gear. There is a latch underneath it facing to the left. Gently pry it to the right, and if both latches are free, the top of the fuser will lift up.
The broken roller should be obvious. Before you move the roller, look carefully at the two black sleeves on the end of the roller. They have to be replaced exactly in the same place. You will need to remove the screw holding the heating element in place in order to lift the heater roller enough to get the old gear pieces out and install the new gear. At this time, the gear is 2.89 from brother. The heater roller might be slightly bent on the end (mine was). It can be straightened. I tried to order another one LJ7415001 but was told that was not a valid part number. The person I was talking to finally agreed to transfer me to extenion 2190 (877-276-8437) when she could not find the number, and hung up on me.

The gear will slide over the heater roller. NOTE:
There are two black sleeves on the end of the rollers. They each have a pair of "ears" on the opposite sides. These will need to be oriented so they are horizontally, and make sure they are in thier slots. BE SURE to screw the screw into the heater connection.

This same procedure can be used to replace the heater element, just don't touch the new heater.

Once done, you can re-hook the top of the fuser, install the screws and reverse the entire operation. A small dab of high temp grease on the gear may keep it operating smoothly. Since the gears are a weak spot, and are cheap, order two so you will have a spare.
Cheers
Woody Baker