1941 Buick 51C (C=convertible) rear seat lights

[3rdowner]

My rear seat (passenger) interior lights do not work. I am having a tough time finding any information about changing the lights (or even accessing the lights to check them), location of the fuse (or if there is one) and turning on the lights manually (both rear doors have spring-loaded “door open” switches but this model did I not come with a passenger light switch).  The front seat does appear to have a removable back cushion, but I have learned to avoid “tearing into” interior assemblies as to avoid breaking the one component which can never be replaced!  Any and all input is welcome.  PS: I have every OE shop manual Buick published, no info on subject.