TOPIC: Troubleshooting Command 2000 Remote Control

I have a 1992 Mercury 3 Cyl 75 HP engine which I have owned for about 2 years. It's a good runner and I've had no trouble with it since I bought it. It started right up in June when I brought it out to launch (in Michigan) but once in the water the Command 2000 side mount remote control seemed stiffer than usual. After using it for about a day, I decided I had better check out the remote and went to the public launch to load it on the trailer. I jockeyed the trailer into place while my wife held the boat from the dock. I needed to raise the engine with the power trim so it wouldn't hit the ramp. When I pressed the up toggle, nothing happened. I tried start the engine and nothing. Thanks to the help of some bystanders, I got the boat out without damaging the skeg and was able to get it home. After checking the electrical connections in the engine and seeing nothing out of order. I removed the remote control and took it apart using a Merc repair guide to break it down. The only obvious problem I found was the neutral lock washer was broken. I'm now waiting for that part to arrive. That may fix the problem but I would like to be prepared to test for continuity between the remote and the hydraulic trim. I hope someone can refer me to a good source to guide me. I should mention one other item. While readying the boat in June, the trim would not work but the engine would spin in response to the ignition key. I check the wiring and found that the wire running to the "up" solenoid (a green wire) was burned through just below the butt connector. The other wire (a blue and white one) had a crack in the insulation. I replaced the green wire with a new connector and spliced it to the existing wire with a crimp connector. I did the same type of repair to the blue/white wire. After this repair, the trim worked without issue. There is a fuse in the circuit after the female plug coming from the remote is connected to the male receiver. I checked the fuse and it is good. There are several switches in the remote box that could serve to prevent the engine from firing. I'd like to get a guide to show me how to test these circuits without removing them from the wiring. Any suggestions will be warmly received and appreciated.