The other side to IBM cables.
IBM mainframe parallel channel cables produced different problems to stretching.
A customer site who had been using IBM mainframes since the early seventies had, by the nineties quite a collection of redundent cables under the 2 foot deep floor. They ran 3 or 4 CPUs on the same foor and had over the years changed 4 generations of mainframes, each new installation needed to be up and running before decommissioning the old one. Not all the cables could be reused or removed, so over the years they built up until in places the floor tiles would need careful adjustment (jumping on) to to fit. When Fibre Channel were added to MFs the cables were more delicate making routeing difficult. It was decided to remove all the redundent cables so a few 'no downtime' weekend slots were arranged with the customer for CEs to be onsite for the work.
For the uninitiated in IBM MFs, parallel cables had 2 types, older 360 era as thick as a mans wrist and later 370 ones ladies wrist size (OK some ladies). The connectors on each end were hand size and there were 2 cables per channel, 64 channels per MF (maybe more on later MF I forget).
Our first weekend pulling cables went rather slowly as we were trying to remove the cables for later re-use (they were expensive). Having identified each end one guy pulled and another threaded the connector through the mass of live and dead cables, lifting and replacing floor tiles as we progressed. Having a run of removed tiles alongside of a few tons of MF could be dodgey, stories of collapses on the social media of the day (pub sessions) were whispered. After 9 hours, 8 CE's sweat had produced little result so it was decided for our next attempt we would cut off the connectors to speed up the job and sod the cable expense. Later we had to identify the longer/heavier cables (100-200 feet) and cut near the centre and pull out from each end. After 3 WEs of this and many cables still to go, management decided 9 x 8 x £double time could impact on their bonuses so they recruited cheaper labour, box shifters, delivery drivers etc.
Next WE 2 CEs familiar with the site and 5 or 6 helpers had a familiarision session on floor tile etiquette (don't let anything above ground change position), how to identify the cables we want removed and avoid the old 360 looking but slightly thicker ones as they are Tape CU to Drive etc. What was not emphasised enough was if more than one cable twitches when someone yanks the end do not cut until you're sure it's the right one; equivalent to the measure twice cut once maxim.
The inevitable happend, twice plus a tape drive. In the end we got away lightly from a customer point of view, losing access to a printer and the tape drive and one path to a tape library were recoverable.
And I did earn a few bob that month!