I was given a Homelite 240 by a neighbor, said ot won't run. So I was messing with it and took off the fuel cap and I can see the fuel filter, If I fill the tank up it starts and runs fine but when the fuel gets lower to where I can see the filter again it won't run. Should I be able to see the filter? I tried to push it down but it keeps poping up to the same spot. How do I get it to stay where its supposed to be down low in the tank.