Previously, I replaced the key switch and starter relay [solenoid], but these didn't solve the problem either. I checked the charged battery fluid specific gravity and output - both tests showed the battery was fully charged and had good output. Removed the starter [do not need to remove the flywheel, but it's a tight fit getting the bolts out], disassembled it and cleaned out the powered [electrically conductive] dust from the brushes wearing. Reassembled the starter with this new kit. This starter drive kit fit/installed fine but it did not initially solve my starting problem on a Craftsman LT1000 mower with a 20HP B&S Twin Engine. This engine takes a lot of starting power to turn it over, and I noticed electrical arcing between the mower power cables and the battery terminal. I removed the power cables, cleaned the connectors and the battery terminals, added star washers between the mower power cables and the battery terminals, tightened the fasteners holding them together and, like magic, the starter turned the engine over/started without hesitation. Anyway, great product and hope this helps others.NOTE: The 20HP B&S Twin Engine requires the starter to draw a lot of power to get it to turn over/started!