Fairly new to this game just started flyin 9months ago, i've had this engine from the start. A problem arose about a month ago, when i set the needle valve on the ground and then hold my model verticle the engine dies after 5-10 seconds. Now if i adjust the needle when its verticle and get it running o.k, when the model is back horizontal its way too rich. I've checked my tank and piping several times and its fine! Can anyone help me?