Blimey, one of the first threads posted on SM back in the day.
The info in my original post is not entirely correct.
It transpires, since working with Ash, the main fix needs to be done at the other end where it connects to the bottom drain of the central unit, not the exit end.
You first do need a new pipe. Once they crush, that’s it, it will always want to crush.
Then what you have to do is half the length of the central drain and trim a bit off the new pipe so it lifts the elbow up and less likely to crush.
Sounds easy...well no, quite the reverse. Cutting the bottom half off the central drain is a nightmare and getting the new pipe, jubilee clip on and cutting it straight with head twisted in the footwell and the steering wheel pushing on the back of your neck...it’s one of those jobs.
Reciprocating saw blade with tape rapped round as a handle is the way forward. Just make sure you don’t feck the cut up and get it straight or your going to be in a world of pain.