I have had this problem on some older Lawn Boy mowers. There are a number of things that you can troubleshoot. First, here is a parts diagram for the rear axle and transmission for your mower... Parts and Diagrams for Lawn Boy 10684, Insight Lawn Mower, 2005 (SN 250000001-250999999) . I would check the following #22- the belt, #4- small pinion gear, take the tire off and check everything in that area(see part diagram) #2- the rear wheel, there is a gear on the inside of the wheel. Here is a better picture of the gear on the rear wheel ...Lawnboy Lawn Boy Lawnmower Lawn Mower Drive Wheels Tires 107-3906 / 117-4104 | eBay . I would check all of these parts to see if they are good working condition. Also check the cable to make sure it is working properly.
If all of these parts are in good working condition. The next thing to check is the transmission... Parts and Diagrams for Lawn Boy 10684, Insight Lawn Mower, 2005 (SN 250000001-250999999) . Take #10- gear case cover off (4 bolts) and inspect the pinion and gear also check #2- small pin to make sure it is intact.
If all of these parts are in good working condition. The next thing to check is the transmission... Parts and Diagrams for Lawn Boy 10684, Insight Lawn Mower, 2005 (SN 250000001-250999999) . Take #10- gear case cover off (4 bolts) and inspect the pinion and gear also check #2- small pin to make sure it is intact.
