If you smell something burning while your washer is running, turn off and unplug the washer right away. A burning smell indicates that something is wrong inside the washer that needs attention. If the washer agitates -- that is, during the wash cycle the motor spins in both directions -- the problem may be fairly easy to fix, although the burning smell may also be indicative of a motor problem. You can troubleshoot burning smells yourself, but a technician's assistance is usually required to fix them.
If your washing machine's belt is worn out, you may smell burning rubber when the washer agitates. You may also smell this if the belt slips out of position. The belt holds the drum steady while the machine is agitating; a worn belt can cause it to eventually stop agitating altogether. Open your machine. The belt is usually around the drum -- you may have to remove a top or side panel to get to it. Examine the belt for cracks or splits as well as making sure that it's around the drum's center rather than off to the side.
If the machine seems to have difficulty agitating or stops agitating altogether, the transmission may not be working correctly. Listen to the machine when it is attempting to agitate. If it hums, the transmission is failing to work. This causes the motor to overheat; when the motor temperature gets too hot, you'll smell something burning. Motor problems must be addressed as soon as possible to avoid damage to your motor.
Frayed Power Cord
A frayed power cord or frayed wires on the inside of your machine could cause the electricity inside the machine to short-circuit, producing an unpleasant burning odor. Check your power cord. If it's frayed, it needs to be replaced. If the power cord isn't frayed, but the outlet it's plugged into looks gray or burnt, a wire inside the machine may be malfunctioning and causing a short circuit. Call your service technician for repair in this case.
What to Do
If something smells like it's burning, unplug the machine and let it cool down before investigating. Troubleshoot the machine using the above information. You can replace the belt yourself, although you should let your technician do it if you aren't confident. Your technician will have to replace the transmission or any electric wires that need replacement on your machine.