The water drains even with the stopper down - American Standard 2770.018W.021 Cadet 5' x 32" Whirlpool, Bone

Plug it .. they make a underwater jb- weld .. works wonders

Try cleaning drain with a length of wire. Strip insulation back about an inch. Turn exposed wire back to form a hook and put down drain and spin, then remove from drain, repeat until hook comes out fairly
clean. Then put drain cleaner down drain, follow instructions with drain cleaner. This should remove gunk that is preventing stopper from working correctly.

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follow this steps and fix it. God bless you
lear a clogged (not stopped) sink or bathtub with a plunger:

1. If you have a dishwasher, pinch off the rubber dishwasher drain hose that leads to the garbage disposer using a clamp or locking pliers. If clearing a bathtub, remove the drain stopper and cover the overflow opening with a wet rag.
2. Remove the sink basket or tub stopper and clean any debris from the drain opening.
3. Fill the sink or tub with sufficient water to cover the plunger cup, usually about 2 inches. If you are working on a double sink, seal the other sink with a stopper so the plunger can create a vacuum.
4. Set the plunger on the drain opening and repeatedly pump it up and down, then pull away sharply to dislodge debris. Repeat if necessary.
5. Turn on warm or hot water to flush loosened debris from the drain.
6. If the clog remains, use an auger (see below) or an expansion nozzle (see below) to clear the drain.

Clear a clog using an auger:

1. Remove the stopper or strainer. If unable to do so, disassemble the drain trap (see below) and feed the auger directly through the pipe. Make sure you have a pail and rags nearby in case of a water spill.
2. Release the setscrew on the auger and begin feeding the cable into the open drain.
3. Once the auger tip hits the clog, set the screw and crank the auger clockwise to break up the clog.
4. Continue breaking up the clog and moving it down the drain line with the auger. Once there is no more resistance to forward motion of the auger, stop and carefully remove the auger.
5. If the clog can't be moved, continue twisting the auger to possibly snag and retract the clog.
6. Once the clog is cleared, flush the drain with boiling water.

This could be caused by the installation. If the installer did not use plumber's putty between the the flange and basin it will not seal with the basin. Another possible cause is if the basin is not perfectly formed it will cause the flange to oval or not seat evenly. If this is the case it may leak between the flange and the basin or the stopper may not seat all the way down and it may leak between the stopper and flange.

if you remove the actual drain mechanism you will see where the drain stopper rod goes into.It`s a hole that works on a lever. You need both hands to insert rod into and then use the other hand to find the right height position to anchor the drain stopper. You insert it from behind and then tighten the drain stopper on the drain pipe. Take your time this sounds complicated but it is quite easy. When you have it lined up you can check the operation of the rod by going up and down.And see if it holds water and then see if it drains the water..

In my part of the country, the type of drain you refer to is commonly called a tip-toe drain because you can use your toes to open and close the drain. Their locking ability diminishes over time and use, and eventually won't lock at all. They cannot be repaired, and must be replaced. You must remove the one you have to get the correct replacement because there are variations in the thread diameter at the bottom of the stopper.
You will need to use pliers large enough to grab around the white plastic underneath the top of the stopper that appears to disappear into the drain. Once you have the white plastic shaft secured with pliers, grab the very top (the chrome part) and twist it counterclockwise to remove it. Once that is off you will see a round piece of brass that looks like the top of a very large screw. IT IS! Using a stantard screw driver, again turn counterclockwise to finish removing the rest of the stopper.
A good hardware store should have a replacement for you. Be sure to match up the thread diameter at the bottom of the stopper.
To reinstall, you can reverse the steps or simply thread the complete assembly into place.

Spring loaded chrome stopper will not stay down to fill tub with water.

Okay, remove 2 phillips head screws at lever handle/overflow.

Pull firmly with much effort and bowing the connecting rod a bit.

Up will come a heavy duty spring on the end of the rod.(prolly a big slimly hair ball too!)

Hope you get the spring, cause that's what works the drain stop.

If spring doesn't come out you'll have to "fish" it out.

Clean everything up real good and flush drain good also now.

The "Secret" now is to put the Lever,rod and spring assembly back in and replace screws and get the lever flipped to the left BEFORE you put the Drain Stop in.

You shouldn't have to disassemble everything in order to get to the trap (elbow joint). Most pedestal sinks are designed so that you can get to the trap from the back (generally after getting down on your hands and knees and crawling around with a flashlight). Most sink stoppers that are worked from the faucet itself have a little bar that extends down the back of the sink behind the drain. It will clip with a little metal piece to a lever that sticks out the back of the drain before the trap. The lever goes through a hole in the drain and pokes into a hole in the bottom of your sink stopper. As you move the lever, you will notice that your stopper goes up and down.

Unclip the rod from the lever and you should be able to unscrew the lever from the back of the drain (don't loose the little gasket that sits inside the screw-cap as it keeps water from leaking out here). At this point, you can pull out the stopper and see what is going on. If cleaning off the stuff attached to your stopper doesn't solve the problem, you can then remove the trap to see if anything is clogging that. Hopefully, by this point, your sink clog has been identified and you just need to reassemble, making sure when you put your stopper lever back in that you actually get it into the appropriate hole in the stopper itself.

If this doesn't solve your problem, it's more serious and you probably want to call a plumber as the issue is either a clog farther along or a problem with the venting of the sink drain.

under the decorative knob there is a screw,this is what holds the stopper in place.if not it should just unscrew.