By way of an experiment I'm uploading this article from my mobile phone.
Today I checked the nearside wheel bearing of 'Pike's' road trailer and I couldn't find any fault with it. As a precaution I re-packed the bearing with fresh grease.
I finally got around to sorting out the sheet by converting it into a continuous one that runs between blocks at each quarter. The sheet is long enough for the sail to be fully brailed to the mast, and it no longer interferes with the tiller as it did when it passed through a block attached to a rope horse.
I'm hoping the new setup will be better than the previous arrangement.