If you can blow through, just think while doing it, did it blow through nicely or did you have to blow a small blockage through. One of the things that used to happen years ago but not so much recently was floaters. Stuff that might float about in your tank for years and just block occasionally. Years back , people would use rags to block the fuel pipe if they lost their fuel cap, dangerous and firey springs to mind but that was common with cars worth a hundred and fifty quid at most back in the day. Another thing was rubber fuel caps of various sizes and they’ve been known to disintegrate and fall in. I’ve heard of crisp packet’s that float then they don’t then they block. Sounds like you’ve had issues before too. Before you disturb anything, you could pop a cheapso endoscope down through the filler cap and actually see if anything is blocking it. The cheapso ones are less than twenty quid for an android device and they have a light on there as well.
Ozziedog,,,,,,,,,,, Floaters !!.