When I first got my Eu2000, it was a bear to start. maybe 20 or 30 pulls.
Since then, I've always put stabil in my gas, and over time, it got easier to start. In retrospect, probably the gas additives broke down the varnish in the bowl.
A couple of years ago, I started to drain the carb bowl after shutting it down and with the switch to off, pull through with the choke on 4-5 times (to suck any remaining fuel out of the carb - and since then, it's the following sequence:
Turn Gen to On
Let sit for a couple of minutes (gas does drain through the vacuum fuel pump into the bowl).
Choke on
Eco Mode off
2nd pull it almost always starts.
I've found that I now need to let it warm up about 2 minutes now - which I didn't need to do before, or when I connect my rig to the generator, it'll stall (Even with Eco Off) in cold weather (below 40 degrees).