Open up the MANUAL RELEASE valve that is on the port-side of the bracket that is bolted to the transom and that holds the OB onto the boat. Typically is is few inches up from the bottom of the mount, on the side where the trim motor is. Use a LARGE bladed flat screwdriver.
Motors also drop down more so by gravity and are not 'really' forced by the tilt ram. Meaning they do get stuck up sometimes and the bypass/overpressure check-valve will open before enough force is applied to the bottom of the tilt ram. Tilt rams have 1/100th or so of the pressure a trim ram does.
You more likely have corrosion built-up on the knuckles around the tilt-tube and possible where the tilt-tube pivots itself. Take a magic marker and mark each largee nut on each end of the tit-tube, then back each off a few turns with a large crescent or box wrench. Spray WD40 or something in there between nuts and side of 'tilt knuckles', also make sure you have greased ANY zirk fittings on the motor.
Only use a premium quality waterproof blue-colored synthetic grease. All OB makers sell their version and it ALL comes out of the same factory, but you will pay 2x to 3x the price for the Yamaha version just 'cuz it wears a Yummie label. By far the best price on this grease is the OMC/Bombardier 'Triple Guard' grease, with Mercury usually being the next cheapest. Tip for you: I buy a large 1-pound tub for $6 and manually re-fill my grease gun tubes.
Clean up the area around those knuckles and apply grease in there, then re-torque using your mm marks as a witness mark. Even cycle the OB up and down a few times (resting 30 seconds each way so as not to burn out the t/t motor) before tightening up those nuts.
You could also try someone putting leverage onto the l/u end while you hit the down button, which just opens the valve. Use that grease everywhere, it is awesome!
