I have successfully used a common 255A  polar relay,
314A polar relays, which are nice because they are sealed and never need adjustment.
and some octal based, tube size, polar relays with no manufacturers named that  I
must have bought at a hamfest so long ago that I almost forgot that I had them.

i have used polar relays on several RS232 devices with no problems.
I saw the idea somewhere on the internet and have used it many times.

Do an eBay search every week for "polar relay"  or "teletype relay" until you
find a real teletype polar relay for a good price.

 very
I just found this one:

eBay item number:22713295371
$25.99 and $7.90 shipping.  That is not a great price, but it is not bad either.

Let me tell you about 925ella. She always has a "make offer".  But if you
make an offer, she never says yes, never says no, never makes a counter offer.
You never hear from her!  So pay her price or keep searching every week.

There is another 314A  from a different seller for $78.33, that is not a good price!

Anything above about $20 for a 255A or any unsealed relay is too much - pass it up!
Unsealed relays need very careful adjustment.

.093  molex females need to be squashed down a tiny bit to fit on 255A or 314A pins..

Maybe someone can recommend a spark suppressor to put acoss the contacts.
.

Tom   N3CRK