#NI
No parts available 11/24/1999 diagram
Primer bulb
Part #N/P
The manufacturer no longer makes this part, and there's no substitute part
Model # 663902121 Official Craftsman gas lawn mower
Here are the diagrams and repair parts for Official Craftsman 663902121 gas lawn mower, as well as links to manuals and error code tables, if available.
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Symptoms for gas walk-behind mowers
Choose a symptom to see related walk-behind mower repairs.
Main causes: damaged cutting blade, loose cutting blade, damaged flywheel key, engine needs tune up…
Main causes: uneven wheel height settings, damaged wheel, dull or damaged cutting blade…
Main causes: engine needs tune up, dirty or clogged carburetor, damaged flywheel key…
Main causes: drive control cable failure, worn or broken drive belt, bad transmission, broken drive wheel…
Main causes: stale gas, engine needs tune up, bad spark plug, dead battery, bad recoil starter, faulty safety switch, ba…
Main causes: dirty carburetor, bad spark plug, clogged air filter, engine choke problems, clogged gas cap vent…
Repair guides for gas walk-behind mowers
These step-by-step repair guides will help you safely fix what’s broken on your walk-behind lawn mower.
How to rebuild a lawn mower carburetor
The carburetor mixes air with fuel to drive the piston. Rebuild the carburetor if it's clogged or leaks.…
Repair difficulty
Time required
60 minutes or less
How to replace a lawn mower recoil starter on an OHV engine
Replace the recoil starter if it doesn't move when you pull the starter rope.…
Repair difficulty
Time required
15 minutes or less
How to replace a lawn mower wheel
Learn how replace a damaged wheel on a walk-behind lawn mower—it's a quick, easy fix.…
Repair difficulty
Time required
15 minutes or less
Effective articles & videos to help repair your walk-behind mowers
Use the advice and tips in these articles and videos to get the most out of your walk-behind lawn mower.
Learn about all the convenient features on our Sears PartsDirect website that make your parts purchases easier.…
Get answers to frequently asked questions about Sears and Sears PartsDirect.…
Learn about the different kinds of mower blades and how to maintain them.…