I think people have confused the low E output with incorrectly adjusted pole pieces, and I have read on a forum in UK where a guy had gone through many 4003 basses to get over his low E problem before purchase and then spreads a word on this ''common problem with Ric necks'' poor chap
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I haven't come across this ''problem'' personally, as it's not a problem with new 4003's as the poles are adjustable, but on the RIHS I have had to move magnets to get an even output.
Problem is on a well set up neck and action, the E string is not in the radius of the other strings, it has to be set a little higher and most pups are set to a specific radius.