Use Google [»www.google.com/ ] to find either file named 5667BridgeFirmware.zip or 5667BridgeFirmware001.zip and it has the instructions and the Firmware file 5667_Tobago_R3[1][2].1.0.bin inside. This recovery requires a serial console cable. Efficient no longer sells them, so you will have to make one.
You will only be able to recover from a failure (Flashing 5667 LEDs) on a Bridge 5667 or update your 5667 Bridge to newer 5667 Bridge Firmware, but at least you will have a working 5667 Bridge again. While this is not the same as Efficient providing you a simpler way to recover your product, at least you'll have something usable. Please note: it does not turn your 5667 into a Router.