Replacing Old Transformer --- Needs to Accomodate Existing Wiring

I have a Nightscaping 1000W 12VAC Transformer that came with the house we boght 3 years ago. It was installed in 2004; the company is no longer in business. Recently, I've come to suspect one of the 25 Amp S type fuses is bad and I find that where I live, no one carries these and they must be ordered online. For that and some issues I have with the very crude mechanical timer, its time to replace.

This transformer had slots for 8 12-2 feeder wires in four Type S fuse protected circuits; in the current configuration, 4 are being utilized. I've replaced all the incandescent fixtures with 6 W LEDs. When the system is fully configured, it will have 25 6W fixtures.

There are actually 8 runs (it appears) in my lighting system, as four separate groups consisting of two 12-2 wires each enter the bottom of the transformer, but only four 12-2 wires plug into each of the hot and neutral terminals. Without completely removing the transformer from the wall, I can't tell what exactly the connections are within, but I'm assuming there are just some wire nuts joining the the dual pairs together with a pigtail then connecting to the bus block.

Looking at various offerings on line, I'm having trouble finding a unit with four terminals to accept my four circuits. Some have four terminals, but the voltage outputs all differ, as if one would pick or prefer one over another, rather than using all of them simultaneously. Am I looking at these correctly?