I did that - Based on the information from Walbro it should be about 1.72mm below the surface, I think it was just a bit below. now it is about 1.7 Maybe this will help.

In the meantime I checked that the main nozzle is working fine so the problem is that it just does not create enough vacum to overcome the spring. So if rising the lever doesn't help I guess I will have to modify the spring. For ther last 24 hours I learned a lot about Walbro carbs