2 questions, defrost & switch

[500sl]

91 500SL

1)
My hardtop defroster does not seem to work. I have made sure that the hardtop is on tight and that the 2 connection pins are in place. Where would I begin to diagnose this problem? Do the 2 connection pins need to go into a designated hole or can they just be put in the holes in any combination. thanks in advance



2)
one of the interior light switches illuminates only one side of the switch (drivers side combo switch-lets you decide how you want the interior lights to function). I'm talking about the switches located near the rear-view mirror. After removing switch cover, I can see two small bulbs that light up the r/l side of the switch(orangy color, very small). The left side is out but the right side works. Do I need to replace the whole switch? Or can i assume that since one bulb works the other just may be loose or something. Also, if I do need to replace the entire switch, where can I purchase? cost? I checked the online shop but it was not listed. thanks for your help gentlemen