I recently took out the lower unit to change water impeller. When i put the lower unit back the first time, the motor started but always in FORWARD. I then took the lower unit out again. This time I put the shifter in Neutral and the Lower Unit in Neutral as well. The motor cranked but very weak and the jump starter drained out very quick. The flywheel seemed to turn very slow and heavily. What have I done wrong? PLEASE HELP!!! Many thanks in advance!!!