Bezoar3784's answer worked for me. It was the needle in the k-cup holder on the bottom that was clogged. Carefully push a paper clip through it. Be careful, because you don't want to damage the spring around the needle. After you clear the grounds with the paper clip, it should work. But it ...
This is the Trip Records rerecording. Recorded in 1975, from 16 Greatest Hits - Trip TOP LP 16-7.