A toilet that will not stop running is usually the flapper or the fill valve, and both are inexpensive parts. What matters is finding out which one, because a fill valve that keeps cycling can push several thousand gallons a month through the meter without anything visible on the floor. We put dye in the tank, watch whether it reaches the bowl, and check the refill tube position before replacing anything.
Weak or incomplete flushes
A flush that starts and then quits early is almost always a tank problem: chain length, flapper timing, or water level set below the fill line. A flush that swirls and drains slowly is a drain problem instead, either in the trapway of the bowl or in the branch drain behind it. Those two conditions look similar to a homeowner and are fixed in completely different places, so we test both before quoting.
Leaks at the base
Water appearing around the base after a flush points at a failed wax seal, a cracked closet flange, or loose closet bolts letting the bowl rock. In older Lawrence homes the flange often sits below the finished floor after tile was added, and the fix is a flange extension ring rather than stacking wax rings. We pull the fixture, inspect the flange and the subfloor, and reset the toilet level and solid.
When replacement is the better call
A hairline crack in the tank or bowl, a discontinued flushing mechanism with no available parts, or a fixture that has been reset several times on rotten subfloor is worth replacing rather than repairing. You get the diagnosis and both prices before anything is removed.