This doesn't directly answer your question, but you can take care of the problem and save yourself a bunch of water by replacing your whole flushing mechanism, with one of these dual-flush jobbies. I replaced mine a while back and am really happy with it. It has different buttons for flushing No. 1 and No. 2.
Amy, quite often the flushing flap that seals off the tank water from the toilet begins to deteriorate and go out of shape. When this happens it looses its ability to "float" until it needs to close. Some utilize an air pocket behind the bottom cone shape others rely on plastic floats. But in any case it simply closes to fast which requires you to hold it open. There are several types of these flush flappers that can easily be installed by anyone. Turn off the water to the toilet and flush it all out by holding the chain or handle open. Once water is out of tank, take a photo with your phone and bring it to the big box store. They will match it up for you and its just a matter of removing the old and replacing the new.
Ideally you should get the non-adjustable kind designed for your toilet.
Or you can as Steve suggested replace the entire flush valve with a new one. Way to much work in my book for a simple flapper change.
Steve G, I went with your idea and replaced with the dual flush mechanism but I still have to hold in the #2 button to get the flush to clear the toilet. The #1 button doesn't have enough flush power to even clear it's own water and I followed the adjustment directions carefully. Since neither the flapper nor the dual flush mechanism work without holding the handle in/button down, what do you think the problem could be?
I'm glad to hear you got one of those dual-flush mechanisms, but disappointed it's not working for you. If you've adjusted everything, have you tried cleaning out the little rim holes where the water enters the tank? They might be clogged. You can check them with a little mirror, and clean them with a wire coat hanger.
The toilet design for dual flush toilets is important. The over the counter duel flush unit does not work on newer toilets as there is not enough water in them to properly regulate the flush itself.
Also depending on the toilet tank design as some have special fill areas to flush toilet any of these may not work with the type you got.
You need to go and get a standard flush and fill valve assembly and return what you purchased. The flapper must be of the same design that is used in the toilet prior to you changing it out.
Ideally you should go to a plumbing supply company with the brand name of the toilet and get what the original manufacture suggests.
Steve, yes I cleaned the rim holes as part of the dual flush's trouble shooting directions. When I flush, the water in the bowl spins slowly and exits with little force. What creates the force of the flush in the toilet? Maybe I need a new toilet (mine is old...1980 or before). All plumbing pipes were replaced in the house 2 years ago.
The force of the flush is dependent on how fast the water is able to exit out of the tank into the bowl. If the flush flapper hole is small water flows slower thus it does not flush as well. An example would be if you took a big pot filled it with water and poured it slowly into the bowl, the bowl would flush but without much force. If you take that same pot with same amount of water and dump it fast into the bowl. It would flush fast and much better. The same thing happens with your toilet. If the flapper opening is smaller, perhaps with the wrong flush valve installed. It will not work very well. Some of these replacement units use smaller sized openings to make them more universal with several brand bowls.
The slow flush and perhaps the reason your holding the handle up is because not enough water is rushing out fast enough to clear the bowl. Holding the flapper up longer is allowing the additional water that normally would not exit the tank to help clear the bowl for you.
Your issue is with the flapper opening. You may need to remove the tank and replace the gasket and connection gasket/seal with one that is larger in opening size along with a new flapper designed to work with this part.
I'm really sorry but I am out of ideas for you, Amy. But it sounds like Woodbridge has some solid, time-tested advice for you.
If this is a 1.6 GPF there is little that can be done to fix the flush pproperly