First of all, welcome to the forum Bobnjo!
Congratulations on getting you new lathe. I don't know the differences between a 400 and a 1400, but the 1400
came out in 1953 as a replacement for the 400. Basic spes are the same, so the differences may be in detail.
It's my understanding that the 400 was the same machine as a Wards 2129.
Serial numbers on Logans are usually stamped in the bed at the end on your right side. You can post it here and I can look up your year of manufacture, or you can look at the FAQ on the Logan website: lathe.com. Lots of useful information there. Some parts are available for these machines through Logan as well: the business is owned by a desendent
of the founder. They don't sell everything, you typically can't get castings, but availability on wear parts and small
stuff is actually pretty good. Prices are a bit high, but they sell small quantities of parts for very old machines so that's to be expected. The fact that parts are available at all is huge bonus: most older brands have none.
In general, I believe the 10 and certainly the 11" machines are different, though there may be some interchangability.
I would email Logan about the headstock clamp. If it's the same as a 10" they turn up on ebay. Mine, which
I think is a shop made replacement is just a piece of 1/2" flat bar with a hole drilled in it. Stuff like the gear cover are most often ebay finds.
We like pictures around here, so be sure to post some of the lathe, and don't hesitate to ask more questions.