Our toilet doesnt flush right because to holes under the rim are blocked by deposits. How can we clean them out? I tried to use an awl and a mirror and cant even get it in the hole it is that blocked. Only 1/2 of the holes are not totally blocked. I turned off the water, drained the tank, wiped under the rim, covered all the holes with duct tape, put CLR in from the tank and let it sit for 10 minutes. That didn't even make a difference!