hi Faithfulsounds.
the mini fuel filter has a very fine gauge gause that collects all the stuff fuel filter misses the rubbish has been likened to the fluff out of yer pocket ,presumably fibers out of fuel filter. you have to dig realy deep to find it although if the spring is missing filter probrably will be as well.
before getting this far ahead though have a look at your fuel pipes sometimes a small rust hole will appear and let air into fuel line ..if you find a problem cut out the rusted erea and use a rubber fuel pipe to replace it
make sure you use hose clamps to prevent air getting in.
rgds.iandouglas