16-12-13, 10:18 PM
If you are confident changing the rings then swapping engines should be easy, although it is a weighty lump and another pair of helping hands would be a great benefit. Obviously you want to be sure the replacement engine is a good one. Using rings that have already bedded in one barrel in another barrel is always likely to allow some blow back and the rings will probably never bed in fully to the replacement barrel. I've done it in distant hard times with the old British stuff with moderate results, but these sewing machines are a different kettle of fish.