Replace o-ring
      C. Fluid level too high
                 Correct fluid level
15. Transmission noise changes, becomes louder
      A. Fluid level too low so that pump sucks in air
                 Top off fluid to fill mark
      B. Damage starting on flexible coupling due to wear or fatigue,            .          .          possible due to misalignment between engine and transmission                       .                 Replace flexible coupling.
                  Check alignment between engine and transmission
      C. Beginning damage of bearings in transmission; torsional
         vibrations, running  without fluid, overload, wrong
         alignment of transmission, excessive motor output
                 Disassemble transmission, replace bearings
                 concerned  and other faulty parts
      D. Beginning damage of gearing; torsional vibrations,
         running without, fluid, overload .
                 Disassemble transmission, remove faulty parts
      E. Fluid baffle on transmission has come loose
                 Disassemble transmission, attach baffle plate
      F. Fluid suction pipe in transmission has come loose
                 Disassemble transmission, fix fluid suction pipe

16. Chattering transmission

Noise mainly at low speed
      A. The engine or propeller generate torsional vibrations,
         which produce a chattering  noise in the transmission.
              Mount a flexible coupling with another stiffness
              factor  between engine and  transmission;
              a coupling with a  higher stiffness factor
              might be  sufficient.
     B. Misalign carbon shafts on input or output shafts
              Mount and align carbon shaft strictly according
              to  instructions issued by carbon shaft manufacturer.
     C. Excessively low Idle RPM
               Raise Idle
     D. Engine not running on all cylinders at idle.