Ok I did the vinegar thing and my Keurig B40 would still give me a short cup. I was about it get a new one even though the current one is probably about a little over a year old and out of warranty. I saw video about taking it apart and blowing air through it, but then saw this one that said to “bang on the bottom…really go to town”. I figured it was worth a shot and surprisingly it worked!
Apparently this fix isn’t permanent. The Keurig is up to its old tricks of delivering short cups :-(