EMG Mk. IX

[Inigo]

Yes! More bass, yet clearer and more balanced sound, and the sibilants much more present without being shrill
Congratulations!
(That's the same quality difference that can be noticed between the hmv no4 and the no5b.. I'm currently playing an old tatty hmv 127 tabletop and switched the original no4 soundbox for a restored 5b, and the sound is overwhelming!)

[Orchorsol]

Yes indeed - even via YouTube the "EMG magic" is very much evident! - and yes, the restored sound has more bass and balance. Congratulations, super result!

[Hoodoo]

It could just be the photographs, but it looks to me like the U-shaped tube of the tonearm on the left has a tighter bend than the one on the right and would not have the proper offset/tracking.
I have crudely drawn in lines to illustrate what I mean.

[Orchorsol]

I think that's probably because the main length is twisted in a different orientation between the two. The base of the left one is approximately vertical, the right is not.