Of course, JJ's bass sound on the early albums was allegedly attributed to him using a cab where one of the speakers had a ripped cone but he hadn't realised until later. His trademark tone had pretty much disappeared by the Raven album and not long after that he'd moved from a Precision to a BB2000, further softening the aggressive edge. Perhaps he recaptured the original sound a little after moving to Shuker basses?
In my live playing days in the early 80s, although we weren't a "tribute" band, we were heavily influence by the Stranglers and we did play quite a few of their tracks as part of the set, always ending with the epic Down in the Sewer. In those days learning a song involved setting the counter on a cassette deck and endlessly playing/rewinding a small section until something resembling the original part could be achieved. Either that or endlessly lifting and dropping the arm on a turntable with the frustrating inaccuracy that involves.
More recently, just for fun, I've decided to try and relearn a few songs and although I've not managed to nail any yet, I have worked out a way which makes it much easier than BITD. Firstly, I import the track into Logic Pro (V11) and use the stem splitter to separate the bass from the rest of the track. Then I 'remix' it with the bass at a higher level and open the result in "Transcribe" by Seventh String Software. The way that allows you to loop sections and slow down the track without changing the pitch make it much easier to isolate and learn the parts and is light years ahead of the way we used to do it BITD.