After months of fighting shifting problems on my OMC800 I finally found the answer. This is not a question, simply a post to perhaps solve the same problem someone else might face in the future. For months the distance between the forward and reverse shift points on the converter box were getting bigger, and the neutral, out-of-gear point seemed to be moving around. The answer was the shift cable. About a year ago I had replaced the outdrive, after replacing the boot. I didn't get the shift cable fully seated in the intermediate housing. This caused more of bend in the cable, which, unknown to me, created a small leak in the cable housing. Water got in and the cable started to rust. The outer cable wires rusted almost through but the core wires were still intact. This caused the shift points to widen. A new cable solved the problem. But, there is a twist to this story. I have a '78 240hp OMC800. When I went to the dealer to buy a cable for it he gave me what he thought was correct. When I opened the box I discovered that the new cable didn't match the old one, the pucks were reversed. The dealer then gave me a shift cable for an '82, which was a perfect match. I installed the cable, and according to the maintenance manual, did the 9 7/8" distance measurement for a '78 while replacing the shift unit. I bolted the outdrive back up and fed the wires into the shift box only to find that they didn't shift correctly, no forward gear! Extremely frustrated, I took the outdrive off and tore the unit back down to the shift cable and shift box. Not wanting to go though that mess again, I took the shift converter box off the boat and began to play with the cable lengths and the converter box. Much to my suprise I found that although my unit is a '78, the person who rebuilt it about 9 years ago installed an '82 shift system. There is a 5" difference in the cable setting, now it works great. Hard lesson learned.
