We have had the spin halyard Harken 29 mm carbo block ruined several times. The same happens occasionally with the main halyard block at the mast base. Usually the halyard eats into the turning part and it gets stuck to the fixed part. Recently went over to a Karver KBO2 for the chute. A really beautiful and well made block!! So far so good...
No problems with Harken ratchets, traveller or cleats. Once blew the becket on the Harken 10:1 base mainsheet block - just tied a dyneema loop through the center of the blocks instead, and it lives on happily in the veteran N20. We tried a couple of Ronstans as turning blocks over the years and were not pleased, so returned to Harkens.