20T Worm Gear Replacement for Snowblower Gearboxes A directfit 20 tooth worm gear designed to restore gearbox function in compatible twostage snowblowers. Matches listed replacement part numbers and is intended for use where the original worm gear is worn, stripped, or damaged. Key benefits Restores drivetrain function: Replaces a worn or broken worm gear to auger and impeller rotation to proper operation. Direct replacement fit: Made to match the listed replacement part numbers for straightforward installation with existing housings and linkages. Minimizes downtime: Quick swap reduces time spent out of service during winter maintenance or emergency repairs. Reliable engagement: 20 teeth profile provides correct gear meshing for smooth transfer of torque in the gearbox. Important attributes Part type: Worm gear, 20T (20 teeth). Replacement Part No.: MTD 91704861 / 91704861A / 9170528 / 9170528A / 71704449 / 7170528. Function: Transmits drive from gearbox input to the auger or impeller drive shaft within the snowblower gearbox assembly. Compatibility: Fits a range of twostage snowblowers that use the listed part numbers, including models from MTD, Craftsman, Bolens, TroyBilt, and Cub Cadet. Verify the part number on your machine before to ensure compatibility. Performance and installation Engineered to match original gear geometry and tooth count to ensure proper mesh and torque transfer. Intended as a direct replacement for the specified part numbers; installation typically uses the existing mounting points and fasteners. Recommended inspection of mating gears and bearings during replacement to ensure full system reliability. Use scenarios Seasonal tuneup: a worn worm gear as part of prewinter maintenance to avoid failure when snow removal is needed. Field after gear wear: Restore auger movement after slipping, grinding, or loss of drive caused by stripped teeth or a damaged worm gear. Gearbox rebuild: Install as part of a gearbox overhaul to renew drive components and extend equipment service life. Notes for buyers Confirm the replacement part number on your machine or in the service manual matches one of the listed numbers before ordering. Inspect surrounding gearbox components during installation; replacing adjacent worn parts may be for long term performance.