Crossover issue.

Would you happen to have a DMM and a tone generator?

The @erik_squires post mentioned…

If it were me I would take out a DATS V2 from Dayton Audio and use it to compare the impedance curves of the drivers and the crossovers to diagnose. 

Assuming that they came out good (the same) then that would exonerate the speakers.
Without that I would more the cross over to the other box and visa versa. Then you can noodle out whether the speaker or the XO is bad, but soldering sounds like a clue to pursue.

Yeah @erik_squires and a less elegant (kindergarten approach) is just to swap left parts between and right…

If one had a scope they could drive both LHS and RHS XOs and plot them against each other.
But you’ve also reminding me that I need to find my DATS.

@erik_squires I did not mean a microphone, I mean to just test the XOs with just a signal and probably some power resistors where the speakers go.

Your idea of the DATS does the speakers, so it is conceptually the same type of thing, just I am aiming it the other way to look solely at the XOs.

Either way we are both splitting the system down the center to figure whether (in your case) the back half is working (speakers), and in my case, whether the XOs are NOT working.

Our approaches are matched (like a Darlington pair).

Ahhh So DATS the speakers, and also DATS through the XOs?