Got a '82 7.5 motor that I use on my duck boat. Noticed that the telltale stopped "pissing" water. Had no idea what this might mean so did some research. Learned that it was more than likely due to a bad impeller. Went and bought a new impeller. I had no idea where the impeller was. Watched some youtube videos and found my impeller. Replaced the impeller..after many failed attempts due to that little metal bar that must get lined up. Anyways, when I was putting the lower unit back on I was having a helluva time getting it to go on. Honestly have no idea why. Finally got the motor all back together. But now that dang thing is stuck in forward. Thing will not shift. As in I physically cannot move the shifter. I am very new to boating. Really only bought the boat for duck hunting. Don't know anything about boats. PLEASE HELP