I had the stern drive off to replace the gimbal bearing and water pump. I am today i tried to get it back onto the boat and it wont go on all the way. I slide the u joint up in to the housing and make sure the shaft goes into the bearing then try to push it on. the unit gets about an 1- 1/2" away from the face of the housing and then it will not go any further. the 6 bolts are lined up with the holes and there is nothing in the way that i can see. feels like something inside the housing is blocking it. i got in the boat and turned the motor by hand and i could feel pressure on the prop so the splines are at least touching. Has this happened to anyone??? please help, any advice would be appriciated!!!!