I would like to clean the filter from this brush cutter and in the instruction book page 21 it shows the screw is on the cover No4 but there is no screw on the cover only on the side after taking this screw off the filter cover will not come away could you please advise how to take it off so that I can wash the filter. Many thanks for your kind help. Regards Frank Mattiuzzo P.S. my phone No is 0417407800