I have a 1973 70hp evinrude with tilt/trim that will tilt up but will only go down about 3/4 of the way. Everything has been working well until now. I usually lower the motor when I bring the boat home so my cover will fit. The last time out I left it tilted up on the trans. saver. Now it will not lower all the way. I have a manual on the motor but it doesn,t cover the tt. Do I have a fluid problem? If so what kind of fluid and how do I fill it. there is no evedience of leaks