Here is a technique my speech therapist taught me. It’s called “find the tension”. When I feel a block, or am stuck on a sound, I freez my mouth/neck/tongue in the position of the stutter. I then try to identify specifically which body part is straining or flexed when I try to say the sound, then I relax that muscle as much as possible and try again. I usually only use this technique if I am really stuck on a sound because it takes a couple seconds and can disrupt my sentence.