broken tap handle?

Hey All,

I have a kegerator now going on 12-18 months, has more or less always worked fine, but today one of the handle was super stiff... I thought maybe because I had set the fridge colder to lager a beer as well. I was able to work it open pretty easily (the line was frozen, it was a seltzer tap, but once I massaged it some it started to flow). Problem was, once I tried to close the tap, it was extremely stuck in the open position... i had to force it back quite hard, and flow continued even from the closed position.

I know a fix is unlikely, I am already ordering a replacement, but wondering if anyone has experienced this and know what could cause a relatively lightly used tap (stainless steel) to break like this.