Samurai's Ichiban Law of Appliance Repair: Never replace a part unless you have proof that the part is bad.
This distinguishes the Samurai School of Appliantology from the Monkey Boy School of Appliance Repair. When I replace an appliance part, it's because I have proven that the part is bad. This proof could be something subtle, like an electrical measurement, or something simple, like laying eyeballs on a burned wire connection. It could be direct, meaning the part is getting proper input but not giving proper output. Or it could be indirect, meaning that all other parts involved in the problem check out good so it's the bad part by process of elimination. This latter technique is more prevalent in the newer appliances with electronic boards where the manufacturer either doesn't give enough information about the board's inputs and outputs or the information/schematics it does supply are wrong.
Samurai's 2nd Law of Appliance Repair: All machines break.
I don't care how much you paid, who made it, or what the salesperson told you, appliances are just another type of machine. And all machines, like everything else in the physical world (including our bodies) tend inexorably toward entropy, i.e., they wear out and breakdown. The corollary to the 2nd Law is to buy appliances that are easy to repair because, at some point during its useful life, you will be repairing it. Speaking of useful life, how long should appliances last?
Samurai's 3rd Law of Appliance Repair: Measure twice, order once.
Ok, you've diligently observed Samurai's Ichiban Law of Appliance Repair and have proven that a part is bad based on some type of objective observation. If this observation involved making an electrical measurement, such as voltage, current, or resistance, then make that measurement TWICE just to be doubly-woubly sure that you didn't make a mistake. Common mistakes in making electrical measurements include not making good contact with your probe and not removing at least one wire from the component before making a continuity or resistance measurement.
Samurai's 4th Law of Appliance Repair: Beliefs are for religion, not appliance repair.
In appliance repair, we use test instruments to quantify the problem and draw definitive conclusions about cause and effect. Hope, beliefs, and wishful thinking don't get stuff fixed, unless it's by pure, blind luck.
Samurai's 5th Law of Appliance Repair: Electronics and wet appliances do not mix.
Manufacturers love using fancy electronical boards for things that used to be done by simple, reliable mechanical switches. I see these boards fail frequently and at far greater expense than the good ol' mechanical switches. But the failure rate of these cheesy, over-priced electronical boards in the wet appliances (washer, dishwasher, ice and water dispensers on refrigerators) is excessively high. If you have a choice when buying new appliances, opt for the models with few or no electronic boards.
Samurai's 6th Law of Appliance Repair: Begin troubleshooting right at the problem.
Where else you gonna start? No water coming in your dishwasher? Start at the water inlet valve. Gas oven won't bake? Start at the ignitor. Go right to the main thing that ain't doing its thang.
Samurai's 7th Law of Appliance Repair: All leaks are visual.
Let's say your washer is leaking. You see the water seeping from under the washer cabinet. So you go online to the Samurai School of Appliantology and say, "my washer is leaking, what should I do?" And we'll tell you to remove the front panel and get some eyeballs on where exactly the leak is coming from. Same deal with your dishwasher-- remove the kickplate and peer underneath with a flashlight while it's running to spot the source of the leak. Get the picture?
Samurai's 8th Law of Appliance Repair: Fix the obvious problems first.
If you have an appliance that you think may have several things wrong with it, you have to break down the problem into smaller component problems and then fix each one. Usually, when you fix the obvious problem first, you find that it was the only problem all along. Other times, you cannot even diagnose the other problems until you've fixed the obvious one(s).
Samurai's 9th Law of Appliance Repair: Nothing kills bio-gookus like chlorine.
Just remember this next time you're dealing with a restricted condensate drain in your refrigerator. Bio-gookus loves to grow in dark, moist environments like condensate drain tubes and they'll restrict the flow the same way plaque does in arteries.
Samurai's 10th Law of Appliance Repair: Never move an appliance to make a repair unless you absolutely have to.
This is one I learned the hard way. You never know what you're gonna run into (that you didn't need to) when you move an appliance. And, worse yet, you may end up creating a new repair that you hadn't planned on. The classic example is pulling a dryer out just a few inches only to find that it had some impossible dryer vent connection that requires a contortionist/gymnast to re-attach. Oy!
Samurai's 11th Law of Appliance Repair: Raw power is dirty power.
All electricity is not created equal. Power quality varies widely from place to place. Depending on where you live, power at the wall outlets in your house could have all kinds of garbage on it. Stuff like voltage surges, sags, swells, and spikes can kill electrical and electronics equipment. In this modern era of using electronic control boards in appliances for the jobs that simple, reliable mechanical switches used to do, all your appliances should be protected by simple surge protectors at the least. Just like you wouldn't (or shouldn't) plug your computer directly into the wall outlet without using some type of surge protection, neither should you expose your appliances to naked, raw power.
Samurai's 12th Law of Appliance Repair: Neutral is not ground; ground is not neutral.
Under normal circumstances, neutral and ground should have the same, or close to the same, electrical potential. But, electrically, neutral and ground are not the same thing and serve entirely different purposes. Back in the old days, they were often used interchangeably, as with the old three-wire dryer and range cords. But, after lots of people got themselves fried or burned their houses down due to a ground fault, "They" decided it would be a good idea to respect the distinction between ground and neutral. Hence the new four-wire dryer and range connections.
Samurai's Golden Rule of Appliance Repair: Never trust customer diagnostics.
I'm too embarrassed to admit how many times I've been burned by violating the Golden Rule. You'll get some customers that are so eloquent and seem so erudite and technically proficient that you'll be tempted to accept their diagnosis over the phone (at their insistence-- to save money, of course). So when you bop on over with the special-ordered part that doesn't fix the problem, you're now in a quandary: how do you charge for this wasted repair effort and the cost of returning a special-ordered part...if you can even return it? Unless you bought the control board here, electronic boards cannot be returned once they're installed. The hard lesson is to always do your own diagnosis, no matter how much the customer insists otherwise.