Part Number:S9574. The hole is slightly tapered so that your motor's shaft will fit tightly. These ones have a slighly tapered 2 mm centre hole. This is important.
HORNBY TRI-ANG WORM GEAR S2375 BRASS SINGLE START WORM GEAR for TURNTABLES
Hornby X8004 Worm & Worm Wheel 0-4-0 Gear Set
Hornby X8809M 0-6-0 Motor Retainer Worm Gear & Pickup Contacts Thomas etc NEW