For plum sauce, combine preserves, white wine vinegar, soy sauce, cornstarch, garlic powder, and ginger in a small saucepan. Cook and stir until thickened and bubbly. Cook and stir 2 minutes more. Remove from heat and cool slightly. Cover and chill.
Combine egg, lobster, pork, spinach, water chestnuts, and garlic in a bowl.
To wrap an egg roll, place the egg roll wrapper with a point toward you. Spoon 1/4 filling diagonally on the wrapper, just below the center. Fold the bottom point over filling; tuck it under filling. Fold the right and left corners over the filling to form an envelope shape. Roll the egg roll toward the remaining corner. Moisten the top point with water and press firmly to seal.
Heat 1-1/2 inches oil or shortening in a 3-quart saucepan or deep-fat fryer to 365 degrees F. Fry egg rolls, two or three at a time, for 2 to 4 minutes or until golden brown. Carefully remove and drain on a baking sheet lined with paper towels. Keep egg rolls warm in a 200 degree F oven while frying remaining rolls. Serve with plum sauce.