Before playing, I almost always brush my teeth and sometimes floss before playing. I thought that ought to be good, so I did not think about cleaning.
For about a week, I was in quandary and in a playing slump. I looked inside the mouthpiece and saw no visible problem.
All it took was a mouthpiece brush to find out how wrong my visible inspection was.
Playing is easy again.
Check your mouthpiece and lead pipe with brushes often.
How often do you clean your horn?