(Older) active PA speaker acts weird

Hi all,

I have a set of LEM Tour Master 12.2 (along with subwoofers), where the one full range speaker acts a bit weird. The system is from 1993, I believe, but they should be of decent quality (Crown amplifiers and RCF woofers).

The speaker plays just fine with no hum until a certain volume. After crossing this volume, the woofer starts distorting a lot. I suspected a blown woofer to begin with, but I am thinking the amplifier is at fault now.
After reaching this volume, when I turn down the volume again, the speaker hums loudly, and it pops loudly as well, when it is turned off. It does this for some minutes even after turned off and on again.
Then it works normally again after a bit of time.

Could this be bad capacitors or something? Has anybody tried something similar or have any ideas? 🙂

Thank you in advance!