So tried the other speaker as you mentioned, swapping drivers I'm getting same result in the working unit.
These two drivers I bought are testing at 5.7 putting out less sound. I used my phone to show the difference. With Woofer unplugged. So only test speaker is running.
Ran the 2 replacements i bought see blue 10 secs, green 10 secs, compared to red 10 secs. Without adjusting volume, there is the jump in volume. To the ear its a big difference.