I had flex PVC and mine were totally blocked. They were collapsed. The guys I hired were able to dig under the deck/skimmer and replace them with regular PVC.

The original main drain is still flex. I think what makes the skimmers go bad is putting chlorine pucks directly in the skimmer basket it eats away on the material over time. Wish I still had the piece that came out-looked like a monster from a sci-fi movie.

Can't do anything about the main drain I suppose. Right now it's still functional.

FYI I paid about $450/skimmer. The "pool" co's were quoting $1,000/skimmer.

I had to run my pool with no skimmers for about 5 years until I got this fixed. It made all the difference in the world. Much easier to maintain.