1. Engine poorly tuned or is new and requires break-in
    Follow the manual's instructions for break in (go here for Pro .15 factory break-in settings), and then for tuning the engine.
  2. Onboard battery pack is not properly charged
    Charge battery completely, or replace onboard AA batteries (nitro models).
  3. Clutch shoes worn out
    Replace the worn clutch shoes and clutch spring with a fresh set.
  4. Drive train is binding
    Remove the motor's pinion gear and roll the vehicle on a flat surface to check the drive train for binding.
  5. Slipper clutch is set too loose
    Tighten the slipper clutch
  6. Over geared
    You must gear appropriately for your environment. Use a smaller clutch bell (fewer teeth). Calculate Gearing.
  7. Missing axle drive pins
    Install drive pins in the axle
  8. Tires slip on the rims
    Glue tires to the wheels.
  9. Stripped spur gear
    Replace damaged spur gear (see article here, T-Maxx example illustrated).
  10. Stripped transmission gears
    Replaced damaged gears
  11. Brakes Binding
    Adjust the linkages for proper operation. Inspect brake assembly for damage.
  12. Damaged Drive Belt (4-Tec)
    Inspect the drivebelts for loose tension or missing teeth and adjust or replace as necessary.