The MLRT1 board has a built-in self test function.
1. Power OFF
2. Turn OFF all DIP switches
3. Make sure your wiring from the MLRT to the LRTs is connected
4. Unplug all MIDI cables from the MLRT1 board
5. Turn ON power
6. Plug in a MIDI cable from -- MIDI IN to MIDI OUT -- on the MLRT1 board
Turn ON LRT #1 -- LRT #1 lamp should turn ON
Turn OFF LRT #1 -- LRT#1 lamp should turn OFF
Turn ON LRT #2 -- LRT #2 lamp should turn ON
Turn OFF LRT #2 -- LRT#2 lamp should turn OFF
If the self test does not work, then check your wiring to make sure all of them are making a good connection at the termination points.
If you get the yellow MIDI indicator light blinking non-stop and extremely fast (pretty much permanently on), then you have connected the MIDI in to the MIDI out while the board is off. Disconnect the MIDI cable, turn the power off. Then turn the power back on and connect the MIDI in to the MIDI out via a single MIDI cable.