About a week ago, it was so bad that I totally dimmed the white LED's for the remainder of the day and until I returned in the morning. There has been no flicker that I can think of since - even when I adjust the whites to mid level brightness (which is when this will happen). You would think that if it was heat it would not happen first thing in the morning after the unit has been off overnight.

I cannot find a bad solder joint. I could re-solder all of the connections.

I got some measurements, but they don't look to be interesting.

20 V across the series string; 4v varying to 0v at the pot connection; my notes don't seem to make sense on the other reading, I guess I better re-test... the PS is a dual output 24V ps.