A quick update: We decided (due to Richard Farrant's suggestion) that we should put an oil groove in the brass bush in the gearbox. Luckily, my neighbour is a precision engineer and he did it at no cost
. He is a true craftsman and set the lathe up carefully, using a dial-guage to get the measurements exactly right. The only way he could do it in his lathe was to make several spiral grooves, rather than a single groove but we saw no problem with that. First he cut an annular groove from the oil hole around the full circumference inside the bush. Then he got the lathe to cut a spiral groove about 1mm deep and 1mm wide from the oil hole to the front at 6mm spacings. That gave three full spirals over the 23mm length of the bush. In one of the pics he is turning the lathe by hand to achieve more control, but mostly it was automated with both axis of the lathe working in unison. The blue tape is there to keep the brass filings out of the bearing. Another small step
