Obstructions will set off the sensors and will prevent the door from closing. Move objects away from the garage door opening and away from the sensors. Your door may open and close properly if you do this. Dirt and debris may obstruct the lens in your sensors and prevent them from working properly. Unlike a rough cotton or wool rag, a microfiber cloth won't scratch the delicate surface of the lens. This could prevent your sensors from working properly. If they are burnt or damaged, cut off the power to your garage door and contact a professional so that they can replace the wiring. Tighten the wing nuts on both of the sensors to make them sit straight in the brackets. Double check that the brackets are attached properly to the garage doors. Doing this will ensure that the sensors are lining up correctly. If the sensor is working properly, it should show a solid green light.
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One-sentence summary -- Clear your garage doorway of obstructions. Clean your sensors with a microfiber towel. Look for damaged or frayed wires. Ensure that the sensors are properly facing each other.

Q: If you're extracting a single shot, you'll probably want to stop the shot once it's brewed for around 20 seconds. If you're extracting a double shot, you'll want to let it go for 20 to 30 seconds. Turn off the machine once you've got the desired volume and the shot begins to turn blonde. Most single shots will be about 1 ounce (30 ml) and double shots are usually 2 to 2.5 ounces (60 to 75 ml). Set the espresso on a small plate and serve it right away. You'll also need to remove the portafilter and dump out the puck of moist espresso grounds. Rinse the portafilter out and wipe it dry. Purge (clean)  the brew head by running water through it for a few seconds and then return the portafilter to the brew head. Consider serving the espresso with chocolate covered espresso beans or a small cookie. You could also use it in a latte, cappuccino, or flavored coffee beverage.
A: Stop the shot. Serve the espresso and clean the machine.

Article: Find the rod attached to a ball that floats on the top of the water and controls the intake of water from the pipes into the tank. This is the floating arm. If you lift up on the arm and the water stops, then your problem is that the water in the tank isn't coming up high enough to turn off and the pipes are getting the message that more water needs to come in, so the toilet runs constantly, or often. A running toilet can cost a fortune in wasted water. While it may seem like a minor inconvenience, a running toilet is a serious and usually easily fixable problem. Sometimes, the floating arm will be bent so the ball will rub or catch on the side of the tank or the tank ball arm. Flush the toilet and see if the arm catches on anything. If it does, just bend the arm gently so it floats freely and can rise to the level it needs to. Sometimes, water will get trapped in the ball, weighing it down and keeping the water from rising as it should. If this happens, dump the water out and replace the ball by screwing it back on. If the ball is cracked or otherwise damaged and allows water in freely, replace it with a new one. If lifting up on the arm doesn't halt the running water and adjusting the floating arm doesn't seem to help, the problem is probably with the flapper assembly, which creates the seal at the bottom of the tank leading to the bowl and connects to the toilet handle by a rod.  Shut off the water and flush the toilet to empty the tank of water. Examine the flapper for signs of wear or corrosion. If you find build-up from the water or other gunk, scour it off with a kitchen pad or a pocketknife and see if you can get the flapper to create a good seal. Also check the opening for the same corrosion issues and clean it. If water still gets through the opening, examine the wire rod that connects to the toilet handle and make sure it's aligned and allowing the flapper to fall freely and plug the hole. Like the floating rod, you should be able to bend it back into place relatively gently, or replace it with a new one. Some are connected with a chain that can become tangled or loose and may need replaced as well. If none of this seems to stop the toilet from running, you'll probably need to replace the ballcock assembly.
Question: What is a summary of what this article is about?
Remove the top of the tank and lift up the floating arm. Check the floating arm for misalignment. If it doesn't seem to be caught on anything, unscrew the ball from the arm by twisting it counter-clockwise. Check the flapper seal.