Linear Serios LS3500 Stereo question

[samjaynes]

In my 2008 Salem 25RKS, there is a AM/FM/CD/AUX system which the two speakers over the slide out are not working. There is a total of 4 speakers on section A, as section B is the outside speakers. What would cause the two speakers over the slide out not to work?

The speakers do not appear to be wired in a series or parallel. Only two wires terminate at each speaker. Looking at the wiring diagram online, it shows only two speakers on section A. Does anyone know how FS wired these systems?

Thanks,