make sure the stern tube is clean on the inside.

Put the cutless in the freezer overnight. Make sure the stern tube is very warm (heat with a heat gun).

Get a wood block and make quick work of it.

If it get's stuck, use a length of 1/2" allthread and some thick wood or possibly steel blocks as "washers" and crank it in.

If it is clean and the correct size, it will go. Make sure you put the setscrews back in if it has them.

Good luck.

rich