I have a lone GRC-9 transmitter. Some questions i have about this:

1. the device just below the power cable on front panel left, what is it ? It looks like some sliding cover requires manipulation, or what ?
2. the brass tube in the cabinet, left side, is that a dessicant holder ?
3. The 4 larger screws in the four corners of the front panel, these are Philips of what size ? I am guessing the previous dimwit owner removed these 4,

found these didn’t allow opening the set, and then of course, lost the screws.

Thanks !

-Hue Miller