Knowing how to fix a broken toaster is a bit like knowing how to wire a plug; it's one of those simple skills that is fast becoming a thing of the past. Just as the majority of plugs these days are injection molded and shouldn't be tampered with, many modern toasters are put together in such a way that once you take them apart, if you do manage to put them back together again they will never be the same. Fortunately, there are some small repairs you can do on a broken toaster yourself, and with replacement costs so low, they are a great place to start if you want to start your own fix-it revolution.
Ridding your broken toaster of crumbs and food debris is the place to start. Remove the crumb tray and shake lightly over the garbage can or sink to dislodge crumbs. Never shake a toaster vigorously, as this will do more harm than good. Never immerse it in water, either. It's an electrical appliance; if it gets wet, not only will it never work again, it will become a fire and electrocution hazard. If a light shake won't dislodge crumbs inside the toaster, use a can of compressed air to blast them out.
Fixing the lever
If the lever won't stay in the depressed position, first ensure the toaster is plugged in, as most toasters won't work unless they have power. If it still doesn't work, unplug the toaster and take a good look at the casing. You will need to disassemble it to access to the lever mechanism. This might be best achieved by removing the base plate, which probably will allow you to bend the contact levers back into position with needle-nose pliers. You might have to remove levers, knobs and fasteners from the end panel, and remove the panel itself and sometimes even the complete housing.
Use compressed air to clean away any food debris, and inspect the lever and carriage. If the contact levers are bent, you should be able to bend them back into shape, though repeating this will weaken them over time, and they will eventually break. If they are already broken, it's time to replace the toaster. If they're intact, check that the carriage moves smoothly. If it is clunky, lubricate it with a small amount of petroleum lubricant, being careful not to get any on electrical parts.
The economy of repair
Other parts of the toaster, such as the element and the solenoid, can theoretically be repaired, but just as printer ink cartridges often cost more than the printer, replacement parts are both hard to come by and expensive. The replacement element for a $6 toaster, if you can get hold of one, is likely to cost more than $10, voiding the benefit of the repair.