Mercury trim question

Running across lake today and power trim stopped working using up, down and trailer buttons BUT the switches at the front and rear of the boat still work. I believe this means the pump, motor and solenoids are good and there is a wiring issue between the controls and the power trim unit? 1980 Mercury Black Max 150, power trim is inside boat and there is a single cylinder on the big motor....

Am I missing anything? Do I need to take control lever apart to check for broken wires?
Thanks for any help with this.

UPDATE: just went out to work on it and it works fine now

Must be a loose connection somewhere, lake was rough and I went a long way with it not working so I thought a bad connection might have worked itself out then. But it did not work when I trailer-ed the boat. The ride home was much smoother but it is working now, prolly will quit working when I put it in the lake next time

Those trim and trailer wires plug together in the control handle.

cool, thanks! I will check there first.