1 Point of View to add to the kettle: swapped out the (4) mast head sheaves last winter, upgrading to Delrin® from 1989 vintage OEM aluminum wire-to-rope sheaves. The new sheaves were procured from Zephyr Werks
https://www.zephyrwerks.com/
The mast was secured to a cradle on the boat, inside storage, with the masthead oriented towards the back wall of the storage building, allowing the ladder to be propped against the wall so work could commence 14+ feet off the ground. Not comfortable, but far better than if working from a Bosun's Chair or harness with the boat displacing H²O, rocking and rolling, which would be far more difficult. As it was, it was plenty difficult, propped on 1 ladder rung, working around messenger lines, pulling sheave pins and implementing a procedure to assure the old/new sheaves weren't accidentally 'lost' down the mast during removal/installation; that would, as they say, "suck".
The masthead of an O-34 are tight quarters, as are most mastheads. The process was made a bit easier because the sheaves could be pulled, inspected and measured before placing the order with Zephyr Werks, making the process somewhat 'Idiot Resistant'.
The 1st hoist(s) of main, jib and kite in May proved the effort to be worthwhile and successful, as all 3 hoists (and subsequent douses) were far easier than the previous season, attested to by 'those that normally jump and douse' halyards (a very scientific measurement).
Back to today's triage. Take care.