I line my cartons up horizontally and prop the back one against the back of the incubator at about 45º. The next one sets up against it, so from the end they look like this:/ / / / / . Then instead of propping up one end, just turn the cartons the other direction: \\ \\ \\ \\ . I put a mark on one side of the carton in the middle, then you can tell if you have turned them correctly. All marks up, all marks down. Works for me!
