Replacements had the correct names; however I did notice the broken four still present in the directory with *.1 suffix.
Unfortunately removing them didn't make a difference: par2cmdline failed again.
phpar2 failed.
MultiPar failed.

Surely I can't ask Shirley or anybody else to repost forty rar parts.
Anybody fancy creating a new par set? 1% redundancy would suffice.
Roughly equivalent to reposting a single rar part.

No hurry. Haven't finished the other ESB sides yet, nor even started grabbing ROTJ.
Thanks in advance to anybody who hasn't yet deleted rar parts after unpacking ESB-Side4