My Kohler single lever pull-out faucet stopped working. Raising up does not start water flow. Turning left sometimes starts some hot water, but raisinglever up and down does not start or stop water flow as it used to. Also seems very tight now.

Fix a kohler faucet
most likely the gasket broke inside the lever, you have to replace it.
shut the water off from the angle stop (valve under the sink) both hot and cold.
use an allen wrench ("L" wrench) to remove the tiny screw around the lever, >>>>before you do that place a rag covering the drain for if you drop it<<<< after that pull the lever out, that will show the inside of the faucet. use an adjustable wrench to remove the actuator from the base. when you get that part out you should be able to see the damage to the gasket. At that point you need a phillips screwdriver to get the gasket out and back in >>>>take the damaged gasket to the hardware store<<<< and get a replacement you may have to change more than one. after you get all the gaskets in place, reinsert the actuator and don't forget to tight it up with the adjustable wrench. center it so it would dispense the same amount of hot and cold water, replace the lever reinsert the tiny screw with the "L" wrench. turn on water from angle valves and test faucet.
that should do it and save you about 300 bucks
if it works for you don't forget to rate me