Change Mechanics to Fix the Yips?

Pickleball is 100% mental and 50% physical...

Experts who advise on fixing the yips generally discuss 2 things - focus and simplicity. Both are centered on correcting the mental aspect. Increased focus is intended to eliminate all thoughts from the mind except the hitting the ball. Simplifying the motion is also intended to eliminate many of the thoughts that complicate the serve, such as target, speed, spin, etc.

One example of this advice is from Deb Harrison in her video Losing the Serve. Deb discusses getting a rhythm to the serve starting with a consistent pre-shot routine. Then, make it simple - get the ball from point A to point B.

Another example is changing the mechanics of the serve as discussed by Jeff Napier in Recovering From a Serving Problem:

You can fix a serving problem instantly. Here’s how: 

When a player is suffering this problem, the ball is usually hit out of the hand. In other words, the ball isn’t dropped to the paddle as the paddle swings upward. Or, more specifically, the ball is dropped only a couple of inches. Instead, hold the ball up higher, and drop it at least twelve inches (30 cm) to the paddle. In most cases, this is all it takes to rectify the problem instantly. In more severe cases, you can try dropping the ball from an even higher distance. 

Or, you might like to try to avoid looking at your paddle hitting the ball, as counter-intuitive as that may seem. Instead, look at where you want to place the ball in the opponent’s court. This can have a magical result in repairing your serve. 

Or, if you’re not serving well, and you have been looking at the destination, try the opposite. Try looking at the destination before you serve, take a moment to fix in your mind where you want the ball to go, then watch your paddle hit the ball as you serve.

Of course, not all experts agree. Norm Davis believes the cure involves 2 parts - tossing the ball a few inches into the air and taking the wrist and elbow completely out of the shot by swinging from the shoulder. The ball toss allows the server to focus on the ball while allowing time to adjust for a smooth stroke. He discusses these ideas in Pickleball Lost Serve.