I have a problem with the tilt trim on my outboard. it goes up and down as it should but leaks down anytime pump is not running can raise engine all the way up and will stay up but anything lower and it leaks. pinching off small pressure hose from top of either cyl and motor stays up seems to be no lost of fluid and level good. Removed the control valve asy and inspected o-rings there but seems ok but still no better. is there any hope for this pump unit or need replacement? any help on this would be appreciated.