The Gang That Can't Jump High Enough - also known as the Knicks - heard some harsh words from coach Jeff Van Gundy about its rebounding problem yesterday but also got some encouraging news. Power forward Clarence Weatherspoon returned to practice after missing three exhibition games to attend to a family matter, and center Marcus Camby, who has played only six minutes in the preseason because of a foot injury, vowed to get back on the practice court this week.