Re: motorguide trolling motor question
Measure the diameter of the smaller of the two shafts. Measure the current length of the smaller shaft. Add the amount length that you need to that measurement and buy a length of stainless tubing that diameter. Remove the shaft from the motor and replace it with the longer one. You will also need to lengthen the wires that go down the tube and make darned sure the shaft is sealed where it goes into the motor. Failure to do this will fill the motor housing with water and ruin it. I would strongly suggest you sell the motor and buy one with the proper length shaft.
As for the manual, your motor is a MotorGuide. The obvious place to start is MotorGuide. They may even have PDFs on their web site. Otherwise, there is always Craigs List and E-bay.