b 1989 85 hp tilt question

"I drained my battery too far and couldn't tilt the motor up to tow it home so I had to manually lift it up so I could put the pin in. It's a '89 85 hp unit. The trim still works, but the system won't hold pressure and from a full up position in about 5 minutes it goes all the way down. I'm thinking one of the check balls isn't seated in the pump. Any ideas?

I mistakenly posted this as a reply to a post - sorry about that.."

On the bottom of your pump is

On the bottom of your pump is a manual release valve. The manual release valve facing away from the boat is your trouble. The 1989 series should be repairable using a small viton seal. You should avoid using standard buna for this seal if you can. Buna won't last long is somebody ever uses oil with additives or ATF as trim fluid.

Since your engine is small HP then you can probably open the check valve and fix it without having it blast apart under WOT back pressure. Alterantively you could get the pump rebuilt for $120ish. But that takes your boat off the water for a couple of weeks.