DIAGNOSIS A hot plastic or rubber smell, especially if it's new or sudden, often points to a mechanical part overheating due to friction. The prime suspects are the drum support rollers, the idler pulley, or the drive belt rubbing somewhere it shouldn't.
FIX Stop using the dryer immediately and unplug it. 1) Remove the lint filter and check the very back of the cavity for any melted plastic debris. 2) You'll need to access the drum area. This involves removing the top and front panels (unplugged!). Visually inspect the belt for signs of glazing, fraying, or if it's jumped off its track. 3) Manually spin the drum. It should turn smoothly and quietly. Any grinding, squealing, or rough spots indicate a seized roller or worn glides.
IF THAT DIDN'T WORK The smell could be coming from the motor itself or its wiring if it's overheating. This is less common but serious. Look for discolored or melted wire insulation near the motor housing.
HEADS UP This is not a "run it and see if it goes away" situation. Continued use with a failing mechanical part can lead to a seized drum, a broken belt, or in worst cases, an electrical fire. If you're not comfortable with disassembly, call a pro—diagnosing this requires a hands-on look inside the cabinet.