1997 11t 5 tnt will not power down

Hi
I have a 1997 115 ,
I just replaced the seals on the main tilt cyl. the new problem is it will not power down, motor works fine, it will go down but their is no " holding Pressure", like I have the manual release open, goes up fine,
any thoughts???

[boats.net]

Probably has air in the system, loosen manual release and lift up and down by hand to purge air out. Top fluid level off each time raise to full up position.

I have bleed the system, untill all the air was out, the unit will not power down, seems like their is a valve stuck open, the unit goes up just fine , but when I power down nothing happens,trim motor runs but no pressure down.

David

[boats.net]

Then would have to take apart and check all valves and seats.