I have a k-10430 that is leaking up by the handle, and down into the base. when you take the handle off there is an orange "O" ring (hard plastic). could this be my problem?

YOU DO NOT HAVE TO REMOVE IT, FIND THE HANDLE SMALL PLASTIC COVER AND LOOSEN THE ALLEN SET NUT

make this steps and fix it. God bless you
f a faucet leaks, replace seals and gaskets . If a shower head leaks, create a better seal or replace seals .
If a sillcock wears out, replace the washers .
If a compression faucet drips from the spout, replace the washer and/or the seat .
If a faucet leaks from the handle, replace O-ring(s), replace the packing washer, tighten the packing nut, or replace worn packing, depending on the valve type.
If a ball or cartridge faucet leaks from the collar, replace worn O-rings .
If a disk faucet leaks around the base or has reduced flow, replace cracked or pitted disk assembly or worn inlet seals
If there is water under the sink, tighten the faucet-set locknuts under the sink. You also can replace putty or a gasket, replace a worn faucet, or replace leaky supply tubes .
If the aerator leaks around the edge, replace the washer in the aerator
If the spray hose leaks or has reduced flow, replace the O-ring on the diverter valve, replace a worn washer at the base of the spray head, or clean the diverter valve and spray head

After removing the oval button cap on the back of the handle loosen the set screw behind it and pull the handle up. The bonnet is threaded so hold the faucet body with one hand (I used a gel hot pad for a better grip) and turn the bonnet counterclockwise. Be careful not to let the entire faucet body turn or it may loosen the bottom bolt that keeps it pulled down onto the base o-ring. Then remove the nut in the same manner and you can simply pull the valve body straight up. To install just reverse this procedure.

The handle has a allen set screw loosen that until the handle comes off then the bonnet nut will unscrew revealing the bonnet cap and washer the cartridge should be under that most kohler's require a special tool to remove cartridge(turn water to faucet off prior to working on faucet,also note how everything is removed it needs to be replaced in same order especially the cartridge,also you should use plumbers grease to coat all seal when replacing everything).

Under the handle, there is a curved trim ring at the top that needs to be unscrewed from the base. This can be on tight due to hard water buildup. I cut two strips of rubber to wrap, one to wrap around the trim ring and the other to wrap base while using channel locks for the trim ring and a pipe wrench to keep the base from turning.

After that is off, you will see a large hex head retainer nut that holds the valve assembly in place. A spanner wrench will get that off fairly easy.

Reassembly is the reverse. Kohler specs the hex nut to be torqued at 9 ft-lbs or 1//4 turn past hand tight.

hi . there should be an o-ring or a piece of dirt under the top . cut water off and take handle off clean and put back together it should be fine. have a good day.

yes a common fault need to replace o ring can diy it yourself

1- Hanldle may have a cap that will come off to access screw to loosen or allen screw on the handle to remove it.
First thing you can check remove handle and make sure the nut that holds stem down is not loose. You can tighten it and try this first just replace handle turn on and check for leaks.

If not please go to step 2 in removal of stem

2- Cut water off and remove handle to gain access to stem. Next remove stem by untighting nut at the base. Remove stem and replace o rings on stem about middle of it. That will stop water from leaking at the base.

base leak is from bad o ring or loose spout very easy fix you can get a washer kit at lowes all you need is a allen wrench(sometimes comes in kit) a pair of channel lock pliers