Piaggio Liberty 125 – Problems with direct-pressure carburettor

Hello all, And this is about my new used Liberty 125. Liberty 125 4T 2V E3 2009 Chassis prefix: ZAPM67100 Engine prefix: M671M Recently purchased with 566 kilometers but not ready to drive. According to the seller it was probably the last 2 years and does not start any more. At the beginning the battery was replaced and new petrol filled in. The first start attempts remained unsuccessfully then the carburettor was built up and cleaned at the same time I noticed that both the E-choke has been renewed and the lid of the membrane has been opened before. Everything apart and cleaned the membrane seems to be fine (no cracks or similar) Then it starts now but no gas takes on and dies again. Sometimes it runs longer in the stand gas sometimes shorter. Start it still gets bad. Petrol tap was controlled. Ignition spark is available. Thank you. Greeting Vll has an idea what I could do to make it run better again.