Per Arnaud's alog, looked at electronics for L1 osems. Found UIM Coil driver unit powered down. Powered unit on, but later found that the unit rocker switch breaker tripped. Continued troubleshooting and found UK satellite unit S1000283 to be missing +14V rail. Replaced unit with new satellite S1100132 to allow for check out/testing of SUS.
Filiberto changed the satellite box and the signals are now alive.