Leaking faucet ff1280r846,1200r692underneath,when lever is open water is running below off spray nozzle..

It sounds like a kinked hose under the sink or a clogged nozzle. Unscrew the nozzle from the sprayer and check for calcium buildup. New parts can be purchased cheaply from the local hardware store, take the old parts in and a sales rep can help you with the correct parts. Some sprayers have replacement nozzles...unscrew the old and screw in the new.

have you tried to purchase a new hose it comes with the
sprayer head shut the water off so no possible leaks take the hose off and see if walmart has one

Clogged sprayer.

take apart the screen on the sprayer and clean it out. run the water through the faucet without the screen for a minute and then reassemble.

Yes the leak is the washer. You can get a new washer at any hardware store. Just take the damaged washer with you and have someone at the store help you.

Here is the washer size according to the manual 20X12X2.5

Page 2 of the link below.

http://www.blancoamerica.com/SPECIFICATIONS/157074R.pdf

Check the hose connections at the spray head nozzle it sounds like it is leaking there and running down the hose and ending up under the sink.

The spray head will need replacing, it unscrews and the new one will fit right on

new plumber

You might try replacing the o-rings but I would replace the cartridge and the o-rings. Be sure and use silicone lubricant on the o-rings.

you can call or e-mail the company, if the faucet is the one in the picture it is a single cartdridge, turn of bith hot and cold water, take an allen wrench into the little plastic cover to remove the handle , unscrew the top cover or it might pop off, that there is either a large lock not or 3 screws holding down the cartdridge, take it out replace it put some faucet frease around all rubber gaskets then install it in the smae way it came out