In one sentence, describe what the following article is about: You want to be sure that you are starting with no sound distortions. The amplifier is usually an aftermarket part that is installed trunk of a car or the rear of a truck. There will be a knob that labeled "gain." Turning down the gain means that the amplifier is not amplifying the signal coming in from the stereo head (the part mounted to your dash). You will not be able to hear anything yet, since your volume is set to zero. This is the best range to use when setting gain because you avoid overworking the stereo head. If you overwork the stereo head you could end up sending distorted sounds to your amplifier. Digital displays make it easy to tell when you are at 2/3 volume, but if you do not have one you can turn the volume all the way up (counting the number of turns) and then turn it back 1/3 of the way. For example, if you turn the volume knob 3 times to get to max volume, you would turn it back down 1 full turn to get to 2/3 volume. Turn it up (clockwise) until the sound (music, talking, test tone, etc.) is as loud as you might ever want to listen to it, so long as you do not hear any sound distortion or overload your speakers. If you do hear a distortion, turn the gain back down until the distortion is gone. Some amplifiers will have a knob that can be turned by hand, but others may require the use of a screwdriver to adjust the gain. Now that your gain is set, you can go back to the driver's seat and enjoy the music.
Summary: Set the volume to zero on your car stereo. Turn the gain on your amplifier all the way down. Power up your stereo and either play a CD or a radio station. Turn the stereo up to 2/3 the max volume. Twist the gain dial on your amplifier. Adjust your volume to a normal level.

In one sentence, describe what the following article is about: These are the screws keeping the rollers and aluminum frame together. They will be along the bottom or lower side of the door next to the rollers. Turn each screw counterclockwise as far as you can. The rollers may come out on their own, but in most cases, you will have to remove the bottom panel to get to them. Do not remove the adjustment screw. The adjustment screw is attached only to the rollers and not to the door itself. Set the narrow edge of the wood block against the upper lip of the panel containing the rollers. Try not to rest the wood on the glass. Tap the top of the block with the hammer to gently ease the panel off of the glass. Each brand of door may have their own type of roller that needs to be used. The only way to identify what type of rollers you need is to take the old rollers out. Go to the hardware or glass store to find an exact match. You may need to put the door back on the track until you are able to find a replacement. Make sure to get 2 rollers so that you can replace both rollers at the same time. Take a picture of the rollers once you find them. This will help you easily buy them again if you need to replace them at a later date. Use the old rollers as a guide for installing the new rollers. The holes for the screws should line up with the holes on the door so that you can screw the rollers into the door. The wheels should face downwards. Line the panel back up with the bottom of the glass. Use gentle taps on the bottom of the panel to slide it back into place. Start at one end of the panel and work your way over to the other. Take the same screws you removed before and reinsert them into the holes on the side of the roller. Use a drill with a Phillips head bit or a Phillips head screwdriver to turn the screws clockwise as far as they will go. Lift the door back into the upper track before setting it down onto the bottom track. If you need to, replace the metal plate, headstop, and screen door back into their proper places. Turn the adjustment screw to move the rollers either up or down until the door moves smoothly. If the door doesn't move, the rollers may be too high. If the door is too unsteady, the rollers may be too low. Generally, turning the adjustment screw clockwise will lower the rollers and turning the screw counterclockwise will raise them.
Summary:
Remove any screws on the rollers with a Phillips head screwdriver. Remove the bottom panel of the door with a hammer and wood block. Identify what type of roller you need. Slide the new rollers into the bottom of the panel. Tap the panel back onto the glass with a hammer or rubber mallet. Screw the rollers into the side of the door. Place the door back on its track. Adjust the rollers until the door moves smoothly.