problem with bose subwoofer, ar159
Recently my bose audio system is not performing well. Subwoofer produces strange scratching sound from time to time. Most often when played aloud (randomly - some frequencies are played well, some not) or when car ignites.
This is stock sound system and it came with the car when it was purchased.
It performed well so far and I never had any problems with it. I always played my music aloud, but now I cannot.
If played on low volume it almost never produces that strange sound and bass is very clear and precise.
Here's what I've done so far to troubleshoot the issue.
I've disconnected the sub (I disconnected the connector on the sub) and the system was performing very well.
I tried to connect and reconnect the connector few times in case there was some lose motion - none whatsoever. It did however made a scratching sound when I connected the connector firmly in place - I tried to move the connector left and right and it always produced this scratching sound.
What do you think is the problem? Is it the woofer or is it the amplifier woofer channel that is damaged?
Why the system performs well sometimes and sometimes it does not?
What else can I do to diagnose the issue?
I have a 10-set bose with classic head unit (not the nav).
Car is 2008 model with blue and me. 2.4 210km engine, if that helps.