Zig, some years ago I had an expensive feeder with a large pivoting anti-squirrel half-dome above it, hanging from a tree. I noticed that the feeder openings were getting chewed up so obviously a squirrel was getting in there, but it seemed there was no way for the squirrel to land on the dome without sliding off to the ground.
Then I was looking out the window one day and watched what the squirrel did. It climbed down the chain holding the feeder and when it got to the half dome it became a gymnast. It intentionally slid down the dome and when it got to the edge it bit into the edge of the dome as hard as it could so that it was able to do a very pretty back-flip and land in the tray at the bottom of the feeder. Poetry in motion, and it then chewed the feeder tubes and ate as much as it wanted. Afterwards I went out and saw a lot of its tooth marks around the edge of the dome (and based on my filling routine this had to have happened in only a couple of days). That little guy/girl was working out as well as any of the young girls working to get on the US Olympic team.
What are ya gonna do? I saluted it and kept filling the feeder until it basically destroyed it.
Good luck with your squirrels.