Yamaha 15 lower unit stuck

I am attempting to repair a yamaha 15 two stroke for a friend. He said the engine "froze up" but this did not happen when he was running it, only after it was sitting for a while. He took off the cylinder head and pounded on the pistons with no success. When I looked at the pistons and bores, they looked fine. If you wiggled the flywheel you could feel the pistons wiggle too. I figured the lower unit was at fault so I unscrewed the shift rod and removed the four lowere unit bolts. The lower unit will drop maybe 1/32 inch but will not budge beyond that point. So what I have is a stuck spline AND a frozen shaft/bearing somewhere. Any suggestions? ( I have gone as far as I dare to go with the hammer/wedges/prying method).

problem solved!

After much prying and wedging the lower unit dropped about 5/8 of an inch and would not go any farther. However, it moved up and down in this range easily. I got some long 8mm bolts and nuts and washers and put the nuts and washers between the upper and lower units. I then unscrewed all nuts a little at a time until the bottom unit came off. Under the engine is a 6" long aluminum housing on the drive shaft that holds the crank seals. this is held on the engine with one ear and a cap screw. This housing was corroded TIGHT onto the shaft. The first 5/8" movement was the aluminum ear breaking off. The rest of the movement was the shaft pulling out of the housing. This motor is only 2-3 years old. I hope this may help someone that has this problem in the future.