Problem with trim tilt on 1987 Evinrude 48 SPL.

The tilt trim is bleeding down and I have searched everywhere for an answer to fix it. It is a single cylinder Prestolite pump that does not appear to be leaking externally. When I raise the motor, it lowers rather quickly from gravity. I have looked for a unit that looks like mine and used about every subject line I can think of in my google searches to no avail. I need to know how to fill the unit or find a kit to rebuild it. I can't find any reference to this particular model and no part numbers for a kit. Any help would be appreciated.

If this is tilt only, go to shop.evinrude.com and look up your motor under accessories. You should find a parts break down.

Single cylinder is a " tilt only " unit.------------Check the manual release valve.

Thanks. Will check the valve.

Screw in valve is tight and fluid is full.

Screw in valve is tight and fluid is full.