[commodor47]

I had a similar issue with our unit and tackled it in 2007. Like you, I found the typical glue removal products didn't work very well, if at all. What did work was tedious and took a lot of time. I used an old, thin, flexible credit card to scrape off as much of the old glue as possible. The corners on the card were slightly rounded making it easy to fit into the dimples of the ceiling and/or walls. Most of my glue overrun was on the ceilings. Acetone will do the trick but it will also remove the paint. Maybe a citric based "goo" remover would work?

Dick