After a recent water main break, our Delta Model 473 kitchen faucet now has very low water pressure. It also continues to flow for a few seconds after turning it off. I tried unscrewing the screen and cleaning it but it did not help. All other faucets have good pressure.

There is normally a filter at the end of the faucet outlet. They usually unscrew. its usually a fine mesh screen with a plastic backing mount.

Yes, go to HD or Lowe's and buy a new one.
Be sure to take the old one for comparison.

Usually these are located in the aerator section of the unit.

from the bottom

it can be adjust take handle off and remove locking collar first turn water off,

it has a metal or plastic ball with a shaft for the handle it may have spun or a washer may be bad under it,

you can get a replacement at lowes or Home depot to replace it if this is the problem .

lume build up. pull handle out and unscrew there should be filter inside take out and soak in a cup of lime away overnite rinse well and reinstall

There should be a nut holding the plate on. What is holding the u-shaped plate up?? You can't tighten the faucet from above. Seems strange the nut disappeared.

This is a view from the underside of our sink. Is this what you were talking about? The steel plate is W-shaped (upside down in this case) and has a single nut larger than 3/4". It's almost impossible to fit a wrench up there to tighten it.

This could be a couple of things.

1. First remove the aerator from the wand and make sure you have plenty of flow with it off.
2. If there is flow clean or replace the aerator.
3. Remove the wand and look between the hose connection and the wand there should be a screen between them. Remove the screen and clean or replace.
4. Make sure hose is kinking under the sink.

If you need a diagram of the faucet with part numbers here is the link:

Delta 470

Hope this helps!

It could be one of two problems, one simple, one serious.

• Easy fix
  

1. Turn off hot water angle stop under sink to faucet.
2. Remove supply line from hot angle stop.
3. Place end of supply line in a small bucket to catch some water.
4. Turn on cold water for a couple of seconds and backflush debris from faucet.
5. Reconnect supply line.
6. Turn on angle stop and test
   

• Complex fix

If you have steel pipes you may be experiencing reduced flow due to corrosion in your pipes. Reduced hot water pressure in the kitchen faucet is usually the first sign since this is the faucet that is most used in the home.

Repiping is a job for a professional. Another symptom you may need a repipe is orange colored or rusty water.