Hello John
Just wondering about a couple of things. Perhaps you have already considered them.
When placing your weight through your hands make sure you are not just pushing through your fingers or fingertips. That often happens as one (perhaps even unconsciously) tries to stop oneself sliding forward. Also one should avoid leaning on the outside of the hands.
Direct some weight through the index fingers (or the inside edge of your hands), anchoring through the knuckles right down through to the base of the thumbs. At the same time seat the heel of the palms and draw the shoulders down away from the ears.
Hope that helps you
Namaste
Gabrielle 🙂