May I ask you to show the extra spotlight?
This is very interesting I'm thinking also to install a kind of this cause the upper plf is too dark and the lights of the translite reflects more light.
Difficult the play in dark room.

Needed picture under working (reflector).
About GI. Its very simple, first check all points of the line starting at the transformer.
Probably it is the contact failure (if the PS works well).

bkgi (resized).jpg

Measure the resistance of this line starting from the connector side at interconnect board.
The ultimate solving : pull out all of lamps and put back one by one and measure the voltage.

One of the sockets or lamps can do the short circuit.