I got a makita line trimmer that runs and starts ok, but fuel shoots out vent hole in gas cap. I took gas cap apart to check on gaskets and venting system. It seems to be just a piece of cut up air filter material - foam type. When i took apart a stihl gas cap if had a hard "ceramic" type of filter in there. where can I find a replacement fuel cap for this machine? Its a Makita RBC 251. Im hoping i can just use a generic venting fuel cap and the threads will match up. BTW it takes about 8 -10 pulls to get it to pop, but Im assuming the lack of pressure in fuel tank is to blame for this.