Nir,
If it's only the midrange that is high, Just raise the jet needle up by moving the needle clip down one notch. This will richen the mixture through the midrange and will lower the midrange EGTs. Raising the jet needle will not affect the full throttle mix or the idle mix. If your EGTs at full throttle are OK, you don't need to change the needle jet; just the needle position. If your EGTs at full throttle are high also, then you'll need to change the needle jet to a larger orifice. None of these changes will affect the idle. You can do that with the idle mixture screw.
It's a good idea to keep a couple of different sizes of needle jets on hand. Changing them is easy and often necessary with changing seasons.
Bill.
