Anyone know anything about NEON signs?

A local bar has a neon beer sign that has been acting really weird. Parts of the sign are constantly moving, sort of like a strobe light. If you watch it, it looks almost like water flowing inside the glass tubes. The light twists and turns from side to side as it "flows" thru the glass tube. While in other parts of the sign, the light flickers from side to side.
Besides that, the sign makes a sound. It's a ringing sound that almost sounds like crickets chirping (when you're outdoors at night in summer). And that sound can be heard above the music in the bar.
Last night the bartender unplugged it, saying that flickering and noise was annoying her. Personally, I think it's kind of fun to watch, especially since it changes from severe to mild, and moves to different parts of the sign in a random way.
But, I am wondering what causes this. Is the sign losing neon, and dont have enough of the gas to glow steady, or is the high voltage transformer (ballast) failing?
No, I dont have to repair it. I'm just curious....
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On Tuesday, August 25, 2015 at 12:47:37 PM UTC-7, snipped-for-privacy@spamblocked.com wrote:

This website helps for repairing neon beer signs:
http://www.steinville.com/neon_repair.htm
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