The guy on the YouTube video made it look so easy. He performed each step smoothly and without hitch or incident. The old, worn parts easily detached from the pipes, and the new parts fit together snuggly without struggle.
He smiled throughout the demonstration, and his shirt was as clean and unruffled at the end as it was at the beginning.
Comments posted at the bottom included “Took me under an hour” and “Saved $400 by not calling a plumber.” I shut down the computer feeling very positive and encouraged. Right then I should have realized I was headed for trouble.