Sorry pjr801 and wolfie, there's no remedy for this recording.
Agree entirely with jctf and mozartfan.
Right from the get-go this was a poor recording showing terrible distortion in the repeated sung choruses towards the end.
I bought the LP when issued and immediately found this track is unlistenable. Most of the rest of the record is OK. I have always picked the stylus up rather than listen to this.
I think the engineers set the levels too high and the sound pressure near the climax pushed into straightforward distortion. Arrangement and engineering by P. Spector?? (not really, only joking).
Obviously this will not sound so harsh on a less critical system.
What a pity!