I have a 1980 Sea Ray with a Mercruiser 228 and MC-1 power trim. The pump is the old Prestolite with the valve control on the lower exterior of the pump. I am having issues with the power trim staying in the up position. Also, the trim motor seems to change tune when I trim down, like it is struggling. There are no signs of any external oil or leaking. The system has been bled and purged of all air. I recently changed the line that goes from the reverse lock valve to the valve control body. When I unhooked the old line, there was pressure buildup in that line with the motor trimmed down already. Looking at different forums, troubleshooting manuals, and the service manual, it seems that the problem is in the valve control body. I have found one online and have it ordered, I was wondering if there is anyone had any other ideas of what it could be. Is there anything that I need to pay attention to when I replace this part? Or is it just the 4 bolts and o-rings?
