For those interested in the outcome - wasn't a power injection issue. It appears to be a problem with the RGB strings talking to the RGB strips (and vice versa). In isolation both work fine, I had it set up as string, strip, string, strip, etc. and whilst the string appeared to talk to the strip, the strip wouldn't talk to the string...... T-Pieces were fine. Had to reconfigure my layout and change all the strips to strings (so had to redo the firesticks, redo the J1sys string set up as well as all of my sequences as the pixel count went from 25 to 50 on the firesticks). That has taken a looong time!! All I can say is thank God I started small this year with RGB and only had 7 elements of smart (4 arches and 3 firesticks). Hopefully my show can now start tomorrow night once the firesticks have been re-erected!