Channel frequency range not balanced

If you think it may be the speaker, and you blew a tweeter it may be the resistor in the tweeter signal path. When you mentioned not balanced that is a trait of two resistors not matched if one is damaged. If one of the resistor is not producing the correct ohms you would experience what you described one speaker louder than the other. 

No disrespect but I think you should call your dealer over to have a look and make sure all is okay. 

True, following my previous attempts to locate the problem I firstly suspected the speaker then later ruled that solution out, although that was months ago. At that stage one of my tweeters had blown so I had disconnected the other.
On the advent of upgrading my speakers for the first time in thirty years, I again thought to source the problem.  Untilyesterday I was convinced that the speakers were balanced.
As for the improvement in the soundstage after reconnecting the cartridge I have no idea, I will play a couple of sides again tonight. I also realaigned and serviced my turntable during the tests, which I believe is important every few months. 

So, you are saying that the fault is with the left speaker. As in the tweeter output? I thought you’d ascertained in the original post it was between the RCA and stylus. i.e. arm/cartridge. And if the cartridge is playing better now, what did you do to fix it at that end? Dirty contacts, loose fitting? Something is not quite right.

Hi, well if anyone who kindly answered is still following, I performed another full channel swop from top to bottom, except that this time I swopped the cartridge channels as suggested here.
Without doubt it is my left speaker that is at fault. However an unexpected benefit came about when I replaced the cartridge wires in their correct order. Suddenly the soundstage `sharpened` up for lack of a better description. The stage became more focused, slightly narrower but more specific. 
Good old vinyl!
I have a pair of demo Monitor Audio SE200`s on hold for the near future, looking forward to that.

Hi,
i believe that you did not have the same problem with your previous cartridge and retiping was performed accurately.
Do one step at a time, most probably cartridge is out of alignment on lateral axis, another cause would be different tube (not same construction) in phono preamp (if you are using a tubed unit).
Azimuth would be the last thing to check and only after everything else is properly set up.

Thanks very much,yes I will swap the cartridge leads,if this points to the cartridge i will use fine shims to hear if azimuth adjustment is the solution.

If you swap the channels at the cartridge, in the headshell, does the bright channel move to the other side? If so, it’s the cartridge.

This.

If you swap the channels at the cartridge, in the headshell, does the bright channel move to the other side? If so, it’s the cartridge. If not, it’s the cable or amps. Or your hearing. I assume it is not on other sources, so it would have to be the phono amp. Is it tube? If so swap tubes etc....