I've had similar problems with unleaded fuel. I purchased replacement generic hose (Goss?) from somewhere like Bursons or Repco. For good measure I added an in-line disposable paper filter. No problems since.
Re Dingocroft remember right now it's the dead of winter in the UK and there's a Covid pandemic of biblical proportions. They were a pleasure to deal with when I bought a replacement fuel tank filler tube some years back.
Cheers, Rob S
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