I've lost 3 flex shafts within a months time while running my KOS. Two have snapped and the 3rd one fell off so I'm looking to replace my shafts with after market shafts.I'm new to boating therefore I'm not knowledgeable of the correct sizes and my local hobby shops are no help. Can anybody recommend descent couplers and shafts to run with my stock motor while I'm in my learning curve?