I have a 79' 70hp Evinrude outboard and I can not get my tilt and trim to work. I had to drain the fluid because the o-ring around the manual release screw was cracked. After filling the unit back up following the manual step by step I still can not get tilt and trim to work. I've tried everything I can possibly think of to bleed any air out of it. The pump is pumping.. I'm at a loss now... anyone have any ideas as to what it could be??