Tonight I decided to get to work on adding two more D cell batteries to my dome. The dome presently has a four-pack of D cells, providing 6 volts to the dome electronics.
All the dome electronics are rated for a minimum of 9 volts, so I've been under-volting them. The top front logic starts blinking after only a few hours due to this, so it's time to add two more 1.5-volt D cell batteries in series.
I located where the two new battery holders will go, and drilled holes for them in the dome ring, using a hand-held drill.
Then I simply attached them with 1/2" #4 screws.
I still need to modify the wiring to get the three battery holders wired in series. I hope to work on that shortly.