ok i have a 1996 120 hp force i just replaced the impeller and i can't get the lower unit to go all the way up, it stops about 1" short, i tried to move the shift lever on the boat, it went on then but i had only forward and no reverse, i know there is a trick to this but i forgot how to do it. any help please. this lower unit gets real heavy after awile, buy yourself. .thanks john