The first SCSI device I had to deal with was a CD drive connected to an XT in a library where I provided one day a week support to the campus. I'd never seen a CD drive before, and had never even heard of SCSI. Fortunately, they'd kept the instruction manuals. Once I'd discounted any change to the software or driver configuration, I took the case apart and looked at the SCSI card: it was covered in grease stained yellow with nicotine (they still allowed smoking in all areas at the time). I checked the cable as best I could; there didn't seem to be any dry joints or anything. The CD drive mechanically worked, but I opened it up just to see if there might be anything which would give me a clue. Nothing. I knew I'd have to call the support number in Canada (this was before anyone offered email support, and indeed a year before we even got an Internet connection to the college).
I rang the number, waiting until 2pm (GMT) when there'd be someone in their office. I was told the expert on that piece of kit only worked afternoons due to a recent illness, so I said I'd call back in four hours and hung up. Unfortunately the librarians weren't willing to keep the place open until 6pm (understandable -- they'd got homes to go to and kids to feed), and I had no office on campus (large parts of which were locked up after 5.30 anyway), so I went home. The house I'd been living in until a month previously had had a phone, but the flat I'd just moved into did not. I ended up making the call to Canada from a pay phone at the crossroads down the road, feeding 10p coins in by the bucketful, repeating "Sorry, what?" as the words of the expert were drowned out by the evening traffic. But he was very helpful and we did get the CD drive working again.