There's no in-line filter between the tank and fuel filter.
Getting the swirl-pot out from the tank is difficult, as the retaining clips are part of the tank base.
There are four of them, and all need to be gently prized off the swirl-pot base simultaneously.
First off, you'll need to drain the tank. I connect a hose to the outlet pipe and a suitable container, then turn on the ignition to the second position. The in-tank pump will then begin emptying the tank, but only runs for a short while at a time. When the pump stops, simply turn off the ignition key, and re-turn the key to position 2. Repeat this until the tank is emptied. Then, feel around the swirl-pot base, and the retaining clips will be evident.
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When the whole lot's removed, you'll need to clinically clean the tank base with some good cloths. This is just about do-able thro' the aperture once the pump/swirl-pot assembly has been removed.
When everything's spotlessly cleaned, refill the tank. I use a clean watering can with a piece of stockinette over the spout, so that good clean fuel is put into it. Remove the fuel filter (again), and fill this with clean fuel too.
Voila, everything should now be okay!