KEY: The butt of the racket will point roughly at the ball if the racket head drops fully. It is a transitional position and there is no pause with butt point up. From trophy position, as your body/shoulders start up and rotating in toward contact, the loop happens. Try thinking pull the racket up to contact with butt of racket pointing roughly at the contact area as you start hand up. Hitting elbow is up high too.
You could even start with a few warm up serves from the racket drop position. In service stance, start with racket head hanging down R side of back and butt pointing up. Toss and serve 10-12 balls from here. Then put racket in trophy pose, toss and loop thru racket drop and pull butt up for 10-12 balls. Then do full service motion and see if you can incorporate the pull up into the motion with no pauses or hitches - smooth and fairly slow motion until you get the feel.
I have a friend who has a very good serve. He racket butt points at the ball. I told him this once and he did not believe me. It was visible if you focused on his motion but it happens so fast and he gave it no thought. But, it happens.