I have a 1972 50hp Johnson outboard, model 5ESL72C that appears to be stuck in gear, will not go into neutral. I have checked the solonoids, checked the switch, and am unsure what type of oil was in it. I read pieces regarding the diode. Does anyone have any diagrams locating this, or diagrams/schematics of the lower unit? What are possible causes to this problem? Thanks for the help.