John Morse posted another interesting article in the Linux group which I've copy'n'pasted below. Email to him did not succeed, so I posted a one-liner in that group inviting him to comp.dcom.telecom; hopefully he'll join us.
Here's John's copy'n'pasted article:
Was your 5XB one of the old original flat-spring models? Perhaps you also had an old SXS switch in the same building?
The 5XB that was beside my 1XB switch where I worked for ten years, was a newer (c. 1966) wire-spring model. I started off as a frameman for the
1XB and 5XB. Never did get the hang of 5XB multi-line hunt and jump-hunt wiring in the Number Groups. The 5XB switchman would work those orders.Another C.O. had three Marker Groups, the largest in the city. Two were wire-spring, but the oldest was a flat-spring model.
IIRC, my 1XB switch didn't have jump-hunt, but did have multi-line hunt (block hunt). It also didn't have TouchTone. Just before I bid out to a Teletypeman slot, I had installed TT converters on all of the 180 old dial-pulse Subscriber Senders (5XB would call these Originating Registers), and then they could sell TT to everybody (Dial Assignment's job became easier).
That old 1XB switch would never give up processing calls regardless of the load. The 5XB was a frail animal though, designed for smaller suburban C.O.s. It could lock up under heavy traffic. A lot of the jam-up was caused by the slowness of the mechanical Trouble Recorder, which punched cards one after another when the going got tough. This caused the Markers to wait on the Trouble Recorder, at least until they timed out and dumped the call. Of course a subscriber just started over again....
These heavy traffic events were usually on Monday mornings right after people woke up to find an ice storm had paralyzed the city. Or after a tornado moved across town, whether it touched down or not. It's amazing how, after many years of listening to the din of the switch, you can get a feel for what is happening. I worked nights, and I could actually hear a call fail by unusual sounds back in the aisles.
I went back many years later and noticed the 5XB AMA Translator frames were jam-packed with jumpers. Seems the Chief Switchman had gotten tired of so many 5-Tickets from lost revenue on toll calls, due to framemen pulling out the wrong jumpers, he ordered no more jumper removal on disconnect orders. That caused a gradual build-up of wire until the detecting loops were choked-full of wire. You could only unwrap and remove a Translator jumper when you had a new connect order for that Line Link assignment. But the framemen wouldn't pull out the wires, so the loops were packed with disconnected tangled wires.
I imagine they also had their share of XET problems (XET = Cross in the Electronic Translator) caused by a part of the wirewrap "spring" breaking off and falling down between the wire-wrap studs. I'd like to have the money the Trouble Recorder cards cost, just for all the XET problems they had over the years!