The set consists of a worm gear 24mm long x 12mm dia with an 8 turn worm screw. The worm has a 2.8mm axle hole which could probably be carefully drilled out to a larger diameter.
The spur gear is 1/4″ (6.35 wide) and 1 & 5/8″ (41.2mm) diameter with a number of regular pitch-concentric 2.8mm holes across the face would be a drilled out to accommodate a larger shaft. This gear has 40 teeth. Both are moulded in an engineering grade plastic.