Hurts to look at those forks Col.
This isn't a repair job,just a service a mate of mine did to his own bike.
He'd recently purchased a TT350,not sure of the year of the model. Up where we are situated you kinda just do your own services,and call on help when you need it for difficult areas.
We headed out to a dam to do a spot of exploration on our bikes. Old mate started his bike,but it sounded really restricted,and didnt have any power at all. I took it for a spin,and said it felt like the carbies are strangled. Anyway he said that up until the day previous it was running ok,then he serviced it that night . Rightio. Asked him about his air-filter,he said "it turned to mush when I poured kero on it to wash it."
Ok lets have a look at what you are using for a filter.
Turns out he used a sock to cover the air filter frame. I asked him why he even would think that'd work,and his reply was,"well my sock had plenty of holes in it so I thought it would be ok."