I bought my toaster over 2 decades ago. At some point the timer/sensor thing stopped working right. No big deal, stick the toast in, when it pops up, push the button down a second time and it gets done. This year it just started working again. When it first went on the blink I tried cleaning out toast crumbs and assorted other basic troubleshooting with no luck. I don't think I did anything between then and now, when it just decided it was going to work again.
I got a microwave at the same time and the big complaint I had about it was that the touchpad was cheaply made and had started to blister and sag. Then one day, after I'd owned it for 15 years or so, I had a closer look at the touchpad. It had one of them protective plastic sheets over it to prevent it from getting scratched during shipping. Peeled it off and had basically a new touchpad for the 5 more years it lasted.