Just an FYI.. your rear speakers are not a result of the stereo.. they get the same signal to process as the other speakers.
Noticed you don't have "rear control" for volume?
The foam surround on the speakers is normally the issue on them. You can buy a kit if your handy and repair them.
Also I tagged a guy on our Facebook group that has 2 stereo's I'm pretty sure he would like to sell..
https://www.facebook.com/groups/2211655775/