Customer had us out because they had a toilet that was continuously running. I got there and found it was the fill valve that would not trigger the float to shut off the water, this happens when the fill valve gets old. I turned off the water, drained the tank, removed the old fill valve, installed the new one and turned the water back on. The toilet now fills properly and shuts off at the correct position. I then check over my work for leaks, which none were found. I cleaned up after myself and showed the customer what I did. I found no further issues at this time.