Your LHS is just pissed cause you didn't buy it from them. The carb is great.
Check the HSN, it may be moving ( from vibration ) sounds crazy but, mine was. Also, don't run it so rich. I know it is not what others say but it is very hard on the conrod. Lean it out some, then run it. You are NOT going to hurt it. There is more damage done in those first two tanks running excessive amounts of fuel than just leaning it and not overheating it. Break-in is just fitting the piston to the sleeve, that's all. Don't race tune it, just lean it enough to drive it. It WILL break-in faster, run better and last longer.
Also, check that glowplug. The first few tanks create a lot of tiny particles (of metal) and they stick to the filament. If in doubt, change it.