From 2010" means your machine lasted way longer than most.

Sounds like a font hill to die on. They paid you, you warned them, and they still wanted it. The mom's opinion is what finally changed their mind, not your professional advice. Not sure losing sleep over a client's bad choice is worth it when you already told them it wouldn't work.

Okay but is checking the pressure really that big of a deal? I get that it fixed your problem, but it sounds like a basic step you should already be doing. Feels like getting praised for remembering to put your pants on in the morning. Still, if it saved three jobs, maybe the bar is just that low for some shops.