Motor floats up in reverse

I have an older 40hp o/b(40etlk) when put in reverse floats up......makes it a bit dificult to back up! What shoud I look for to correct this problem? thanx in advance for any help you all can give me. joe you can email me directly at ahhgofigure@aol.com

[boats.net]

Power tilt unit may need to be rebuilt.