According to Deere.com, the John Deere L100 lawn tractor is optimized for use on properties of up to 1.5 acres. The lawn tractor features a belt-driven mower blade that you can raise or lower to meet your specific mowing needs. After a period of moderate use, your L100 mower's drive belt may start to stretch, like any mower belt. The belt can break in extreme circumstances. When either of these situations happens, your mower's blade will no longer spin. Fortunately, you can replace a L100's damaged drive belt with minimal disassembly.
Things You'll Need
4 wooden blocks
Park the tractor on a level surface and place a wooden block or similar objects behind each rear wheel and in front of each front wheel. Pull open the tractor's hood and disconnect the spark plug wire so the engine is incapable of starting while you are replacing the belt. Disconnect the plug wire by pulling sharply on the rubber boot.
Locate the mower height adjustment lever on the tractor and set the mower to the lowest possible position. This will reveal the belt pulleys on the top side of the mower assembly.
Use a 15mm socket wrench to loosen the tension on the pulley just beneath the seat on the tractor. There are two pulleys for the belt: the smaller pulley beneath the seat, and the larger pulley near the front of the tractor.
Slide the smaller pulley toward the front of the tractor to release the tension on the existing belt, if it is present. Remove the belt from the pulleys and throw it away.
Wrap the new belt around both pulleys inside the tractor. Slide the smaller pulley toward the back of the tractor until the belt sits tightly on both pulleys. Tighten the 15mm tension bolt, raise the mower blade and reconnect the spark plug and battery cables.