My cousin told me my sourdough was 'gummy' and to check my oven temp with a $12 thermometer, which showed it was running 25 degrees cold. | Baking Fails And Wins - Vivisector
That cousin did you a solid, honestly. Oven thermometers are cheap and they save so much frustration. Mine was off by almost 30 degrees for years, and I just thought I was a bad baker. Now I keep one in there all the time and check it every few months, because the temperature can drift. It's wild how much that small difference messes with bread and pastries.
Oh man, that reminds me of my old apartment oven. It had a mind of its own. I tried to make cookies and they'd burn on the bottom while staying raw dough in the middle. Turns out the heating element was totally shot and the thermostat was just a liar. I gave up and just used the toaster oven for everything until I moved out.