[Seaking]

Change all the fuel lines including the line inside the Fuel tank.
Set the needles to the manufactures specs
next time you start the heli Pinch the fuel line to the carb until the engine dies and time it,,, should be around 6 sec's or more on an engine that is set rich ,any less than that then Richen the lower needle

When you get it to around this time frame spool the heli up into the hover and land again after a few minutes of flight and using your finger place it onto the backplate of the engine as soon as possible after landing, start counting 1,2,3,4, etc
if you can can count to 7 or 8 before you have to move your finger then your needles are in the right area for a beginer , any less than this and the engine is too lean so richen the top needle.. If the count is less than 3 or 4 richen the bottom needle first try again then richen the top needle

Roger