I have a Johnson 70hp model 70ESL74M. The control box (which is Powershift II) that runs this unit is messed up. I have taken it apart, cleaned it, put new grease and insure that the cables are loose. Put it back together, shifts find until I hook it up at the engine. I can shift it a couple of times and then it locks up. I can move it forword but not in reverse. It has me stymied. Now It will not go into the complete neutral position so I can start the engine. Any ideas out there.