Halyard Through Mast Guides

[Cacique]

Hi I have a 1977 Kemp mast, where the haliyards exit the mast there is a 1" hole with a pulley device that has a small pulley inside the mast and another on the outside and they guide the halliyard from inside to outside of the mast. On my boat a Vancouver 27 cutter I have 5 of these on all but a couple the pulley on the inside is seized, I've tried penatrating oil, soaking for several weeks, boiling for 1/2 a day, brute force etc but I still can't free off the pulleys does anyone have any ideas? Thanks.