You went thru every step outlined in the post of the illustrious, Chiefs post ?
You have a fully charged battery of course.
If yes... disconnect the battery run to the center pos. post of the tilt solenoids, a battery cable straight from the pos side of your battery.
See the brass strip that bridges the 2 pos sides of the solenoids.
Remember to disconnect the battery both sides. You run from the solenoids to the pos side of the battery and then last connection will be the neg side of the battery.
I you for any reason do not understand this reply post your question here and i will try to explain better.
I still think you missed something, you didn't clean out the clutch housing, the clutch plates are rusted, something. The base of the tilt solenoids are the ground they sit on a metal bracket, and the ground goes thru to the mani or block, bad ground ? Also there is a ground on the bell housing actually the back with a thru bolt the wire is in the back.
That was removed and cleaned ?
It is in the 1 or 2 o'clock position port side. " right side looking at the stern with your back towards the bow "