VFR2

Hey i have a lexus is 350 F 2016 Car with the mark levinson audio, I noticed an issue with the rear back window of my car while blasting music. the audio becomes very shaky. one of my friends said it might be the subwoofer causing the issue. So I'm wondering if there is a quick cheap fix for the issue or should i totally Replace the subwoofer. And also if there is a video that can show me the installation of the whole process. Thank you in advance <3