Shifting issues 1965 omc

Been working out all kinks in

Been working out all kinks in my 1965 Cruisers Inc with a OMC out drive/ GMC in line 120 HP 4 cyl. and my latest hickup is that when backing out of the dock the outdrive has trouble switching from reverse to forward the first couple of tries and then forward finally locks in. The other issue is at higher rpm (3500 and above) it will switch from forward to neutral occasionally. My first thought was maybe the bushing in the prop was bad so I switched props and that had no effect on it. I did have new a new water pump insalled and I reinstalled the lower unit recently myself. I am pretty much a rookie to all this as this project is my first boat. Any thoughts out there?
Dave

"Sounds like a wire got stretc

"Sounds like a wire got stretched or rubbed thru and is occasionally shorting. You might have a bad shift switch. Either way you should go back to the connectors and hook up a light in the circuit and see if the problem is in the controls, (flashing light)or more sinister.(steady.)

Next check your voltage going in while it fails.
Finally if still a mystery, Hook a single wire to the shift at the transom and straight to the battery. You need a "wire baby sitter" for this.

That will remove everything from the shift circuit except the lower unit and it's wiring. Let us know how it goes.

Was one of the jobs just finished a lower unit oil change? Those electric shifts take a special oil."