Sorry, but I have to be the voice of dissent here! I repair machines, and often lay them on their side to get at the screws on the bottom of the machine. There is no other way to get to them, and the machines are fine. They often stay that way on the workbench for a week or more when waiting for a part, with no bad outcomes at all. Go into the back room of any repair shop and you'll see machines laying on their backs waiting for parts. It makes no sense to reassemble them while waiting, it doesn't hurt them. The only way I can see a potential problem is with some machines and older sergers, they have an oil reservoir..the oil would seep out everywhere if a machine is laid down without draining them first. The only other thing I warn against is when traveling with a computerized machine, let it come back to room temp before you plug it in.