1996 Mercury 125 stuck in reverse. This is the 2nd time. 1st was shortly after I got the boat it locked up and I repaired it. Upon repair found the shift cam broken badly. Has been working good until the other day I backed out from dock and started to move controls to forward and it would not move forward. Any ideas what the cause is and what to look for when repairing?? I assume I will find the same problem due to it acting just as it did before. But this time there was no excessive noise or problem going to reverse. Thanks