Where does washer go for 12h-6h/c stem from Danco for faucet?

You may need to replace the cartridge(s) or rubber washers on the valve stems. Depends on what model faucet you have.

Change the O rings in the mixer.

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2. Thanks to Danny Paccho I purchased a wrench to use in removing the sleeve from Geers Plumbing


3. Then , removed the \'87 Price Pfister faucet housing from the basin by disconnecting the 2 pipes under the basin and removing the top basin nut; inserted the wrench into the top, turning counter-clockwise until it locked (er tightened a bit) and hammered it out ,gently?, to not damage the escutcheon threads , or the basin nut.
   

change cold cartridge call danco if you can

first off, put the spring in the faucet big end down. then put the black rubber boot seal in next and push it into place. Then place the Stem in but be sure to line up the notches before you screw it all down. I hope the will help you....

I would say it is a washer on the stem, here is a website that will assist you:

http://www.pricepfisterparts.net/

Sometimes on the stems on the side the handle attaches is a nut that can be tightened. Inside this nut is a rubber or other type of seal. tightening this nut stops the water from coming out of the handle. If the nut has already been tightened then possibly need to replace this rubber seal.

#1 THE FAT PART OF YOUR SPRING GOES INSIDE THE FAUCET ,AND SIT ON THE VALVE BODY(SEAT)
#2 THE LITTLE BLACK WASHER SIT ON TOP OF YOUR SPRING
#3 PUSH THE STEMS IN THE CORRECT SIDES HOT ON LEFT.CAUTION THERE IS USUALLY NOTCHES ON THE SIDES OF THE STEMS TO HELP YOU ALIGN THEM IN THE VALVE BODY,
4 PUT THE NUT BACK ON ,TIGHEN SLIGHTLY,TURN ON THE WATER TO CHECK ,IF OK RE INSTALL YOUE HANDLES

The stem and washers inside the faucet need to be replaced.

If you Do it yourself the parts typically will cost you less than 20 bucks.

Most plumbers will charge 75 to 100 for this relatively simple Job.

You can order parts directly from the manufacturer, or from a local plumbing supply house.
The faucet may still be under warranty and the parts would be free. Here is ther number for Price pfister.
1-800-PFAUCET (1-800-732-8238)