Some folks really shouldn't attempt home repairs themselves as they simply have no idea what they are doing. When I bought this place I noticed that the cold water valve in the bathtub had a slow, steady stream no matter how tightly you twisted it off. Obviously a bad washer.
Today I finally got around to taking the valve apart to replace the faulty washer. When I got it apart I noticed that someone had previously tried to fix it and had used a flat washer. The compression marks on the washer suggested that the valve seat was concave, not flat. A quick check with a flashlight indicated this to be the case.
I guess whomever had attempted the repair had no clue what they were doing and had chosen the wrong washer and the result was a failed repair. They had also tightened the washer retaining screw far too tightly so that even if they had used the right washer it would have still leaked. The thing I can't understand is why they chose to just leave it that way instead of finding someone who did know what they were doing to determine why the new washer failed to fix the problem.
I disassembled the valve assembly and installed the correct convex washer, reassembled everything, and restored the water supply. No more leak, just as I expected.
I've always been a do-it-yourself kind of guy, but if I am not sure of what I am doing I will at least make an attempt to learn about the repair in question before attempting it. I just can't understand someone blindly attempting a plumbing repair, even a simple one such as this, without taking a few minutes to educate themselves on how the device works, the parts involved, and the styles and types of variations of the device. It saves a lot of headaches and expense.
Some folks really should just call in a professional and let them make the needed repairs for them. I'm sure the water wasted by that leak cost them far more in the long run than a plumber would have charged them to make a simple washer change.