i don't really agree. I'm in the 'you should rebuild' group.
There are numerous important fundamental things that you are not doing.
For one, the serve has to have a rhythm. Yours doesn't have a rhythm from the start so that manifests itself later on at several points in the swing.
For example, ideally there shouldn't be any pauses or hitches. Easier said than done I know but I count 4 pauses/hitches in your swing. When you first set up their is a small hitch where you're holding the ball out in front still. You set, start and then stop very slightly and then start again. Then after you toss there is another pause. Then as your getting ready to swing there is a small pause and then very quickly after that there is another one. Each time you pause you lose stored energy and you have to expend energy to hold some other body part in place. That means muscles are tightening. Then you have to use more energy to restart those stopped parts and then things are out of sync. Also your knee bend is too late. You should be going down in sync with the toss.
Also your feet are messy. You start in a platform and then move into a pinpoint which is ok but it's not a smooth transition. You move your right foot forward and put it next to the left. You might want to consider dragging the right foot here up to the left which a lot of ppl do. It's smoother. It has momentum. You just place it there which is ok but when you place it there your whole body kind of stops. Then instead of using that position as your base you move your left foot away from the right foot. And then sometimes you adjust one or both feet again after that. That's a lot of shuffling.
You're not pointing at the ball with your left hand. It's extended up but it's not pointing. You should point up at the ball
for as long as possible. This also gets you into having a cartwheel motion. You don't have any cartwheel shoulder action going on which is like wta serves. You also don't have any torque. Pete and Roger have their torso twisted and facing further past the side fence towards the back fence. Your torso is facing the side fence. Their legs are bent and on their toes and springy and their weight is loaded. Your legs are straight, knees locked and flat footed. They start the swing by pushing off their legs using ground forces. You start with your arm and then bend and push off the legs. Their left shoulder is up and right shoulder down (cartwheel beginning). Your shoulders are horizontal. They go towards the ball with the butt of the racquet and hit the ball as their body is going up. You go at the ball with the strings and slap the ball as your body is falling down.
If you stop your vid at 24s here you are holding the racquet way to far to the right of your body as you toss. Also your palm and the strings are facing the net. They should be facing the side fence. This is contributing to the waiter's tray. Also your elbow is all the way down to hip level. It has to be much higher. And you should be leading the upward swing with your elbow.
If I were you i'd work on getting the feet figured out because that's the start. Then work on getting into a pretty trophy position. Then work on smoothness. That way things will work themselves out.
Or you can band-aid everything