Interior lights, some stopped working and some are intermittent

Hello all,
On my 1998 Marathon XL, 3 of the 4 driver’s side galley lights have stopped working. Then 2 of the 4 galley cabinet lights stopped working but now they are intermittent. Also 2 of the bedroom lights stopped but now the are working again.

Since there are several switches that control these lights there has to be a central box that turns power on and off. Any help would be appreciated.
Thanks,
Mark

Attachment 16001
Attachment 16002
My problem is probably in one of these Power Switch boxes. Any ideas on where to look first?
Regards,
‘Mark

Those are transfer switches. So, it won't be them.

Another lost sheep. When u bought that bus did u get any instructions?