Repartee wrote:

Which is too bad, since a search for other Selectric II's for sale seems to return about 70% as-is, for parts, needs repair and etc. So I gather they have passed the end of their useful service life, and keeping one functioning will be expensive. Is it the complexity of the mechanism?

I too share in the admiration of the IBM engineers who designed the Selectric. The main obstacle to the repair of a Selectric is finding someone who actually knows how to fix them. The CE's that IBM trained back-in-the-day are past retirement age or past away. There are few still around who successfully repair them. Most shops will just say they aren't worth fixing or the estimate will be outrageously high.

Don't despair. They are sturdy, well-built machines that can still provide years of service when properly repaired. You can teach yourself with the manuals online or seek a knowledgeable repairman. They do still exist.
 

Possible. A photo would help. IBM contracted with various manufacturers to make the housings and each one used a different date code stamp.

Oops, I forgot. Non-USA elements have 5 digits.
The entire part number for your element is 2431595, with the last 5 digits cast into the top of the element.
I have some Canadian elements for the Selectric III, but I'm not sure they would have all the same characters as your element. I have a Courier 10 & 12-pitch and Letter Gothic 12-pitch Canadian-English elements for the Selectric III.

My Selectric III is a 92-character machine (yours could be 92, 94 or 96, (the number of character keys doubled)), so it won't type all the characters on the element, but I'll type you a sample of all the keys I can if you are interested. I would take $10 each for them, plus shipping from the USA.

 

Aha! The Selectric I's with the plastic (polyester) cases were made towards the end of production, so you do have a later model, definitely from the 70's. The casting dates molded into the covers are sometimes covered by the foam insulation.

It is hard to date IBM Selectrics from the serial number alone because they were produced in so many factories around the world. I can usually date the machine by inspecting date codes inside the machine. Usually the cover castings and motor have manufacturing dates. Also look for the install date on the sticker on the bottom of the machine (if there is one).

In IBM terms, the "21" in 21-0776906 is the Product Code which means it is a Selectric I. This number is not always part of the serial number and most Selectric I's are known as 7x or 7xx models.
The Selectric I models were produced all the way up to 1977, concurrent with Selectric II's. By looking at your photos, I'd say your Selectric I was a later model, probably from early 70's.

Uwe is correct about the date for the Selectric II.