Intermediate line that's lost it's sink

Now that Spring trout season is likely over I'm going to focus on my gear for the Fall. I use Airflo intermediate line and I love it. No memory and casts like a dream. The recent issue I'm having is that it won't break the surface tension without waiting forever. I've cleaned it, rinsed it to no avail. It's 6WT line.

Has anyone experienced this? It sank fine when it was new. I replaced a clear intermediate Orvis line that sinks but has horrible memory. I'm not sure if the line properties changed or if the pollen on the water increased the surface tension? Maybe I should have gotten heavier line? The old countdown method isn't going to work if I don't know what my sink rate is.

Thanks!