Using his favorite treats (which were reserved for grooming training only), I first taught Raffi to touch the clippers with his nose while they were off. Once he was doing that happily, I would have him touch them a few times and then place them against his muzzle, top of head, under ears (slow progression, starting with one area at a time). On alternate sessions I was getting him used to the clippers turned on. Placed at a distance, turn on, treat, turn off. Gradually bringing them closer and leaving them on for longer. Always a treat as soon as they turned on, more treats after letting it run for a bit. It didn't take long for the sound of the clippers to set his tail wagging lol.
Then I brought the two parts together. Started back at the beginning with having him touch the clippers but this time while they were running. And then following the same initial progression.
It sounds like a lot written down but doing 1 or 2 minute sessions a few times a day, it can progress rapidly.
Separately I also worked on handling his face, stretching lips and moving head up and to either side.
I started off trying to do it on the grooming table but at the time I had no experience with it, so I think my nerves made it worse.
Once I bought the right clipper, I sat outside with it and had her come to me and did litte bits at a time, I'd stop and let her run away,
clean the clipper, put it down, pick it up and call her, at first she would come slooowly, do a little bit more, until she got restless, then release and repeat.
It took several times to get into a rhythm where when I picked the clipper back up she would come without being called.
I watched a lot of grooming videos and some of my favorites come from this forum. I was especially impressed with the ones that sat outside with their poodle
un-tethered and despite minor distractions, got the job done. (my most fav is the feet one, she is so confident which I was not.)
I think with dogs it is very important to keep a vision in your mind of what you want to happen and project it.
So I would watch those videos and hold them in my mind while we worked through it. I did have to get used to half-baked grooms for a time, but I got over it.
Nowadays her face takes 3 minutes on the grooming table, and she actually comes running when I pick up the clipper. She enjoys being groomed which I never expected.
But I procrastinate and let it all grow out and scissor with blunt end around her eyes until it is definitely necessary. I'm not that good at it yet.
Are you an experienced groomer? I think confidence and efficiency can really make a difference. I think I traumatized Gracie with my clumsy, overly careful attempts. It would drag out for days. She never got comfortable with it (and, to be honest, neither did I).
What about using a professional groomer to help get your puppy comfortable with the process, and then you can just do maintenance until it becomes less stressful?
PeggyTheParti brings up an excellent point. Professional groomers are confident when they hold the dogs face to groom. That’s important. You might want a two pronged approach to this problem
1. Take your dog to a professional groomer to have the face done before you have done the second part of desensitizing.
2. Work on desensitizing the face to the noise and vibrations of the clippers and being held Still on the face. You can even start by desensitizing to an electric toothbrush where you have noise and vibration but no potential to actually shave as the first step. Or just use clippers. Very short sessions where you touch the face and treat. Start with it in off. You can also turn it on near the puppy and treat for short sessions. Once puppy is comfortable with both touching and noise you can start quick touches with clippers on the face then build up to longer. Treat and praise to reward as you do this.