I was under the impression that the 401 and 401A were the same machine, but just didn't put the model number on for a while. So after some research, I found that the 401A sometimes had the model number on a tag under the badge on the pillar and some had the model number on the stitch length plate. I wasn't aware that there was a 401G made in Karlsruhe. It looks like the ones made in Germany would probably have serial number that start with PA, PB or PC. There is a picture of the 401G at
https://4.bp.blogspot.com/-prhlMFjMD...s1600/401G.jpg The easiest way to tell the difference would be to see what looks like two take up levers above the tension assembly on the front of the machine.
The 401A with the model on the stitch length plate can be seen at
https://img1.etsystatic.com/005/0/68...91251_ld6t.jpg and the 401A with the tag below can be seen at
https://millardsewing.com/wp-content...06-600x450.jpg The 401A serial numbers would start with NA, NB or NC
The serial number can sometime be hard to read, it is on the under lip about half way from front to back on the left side of the machine. Even knowing where it is, I had to shine a flashlight at different angles to find it and be able to read it.