I have Polk audio M5 surround speakers on short speaker stands. One of these got accidently knocked over by my kid. Now I hear something heavy loose and sliding around inside the casing if I tip the speaker at an angle. I am trying to find any screws or anything to get the casing open to see the problem but there does not seem to be any way it can be opened. What can I do at this point other than buying a new pair of speakers (not Polk ever again). I will appreciate any suggestions. Thanks in advance.