You don't seem to be having a lot of luck with your flock. Sending loads of positive vibes!
Have you tried making a very fine chop and sprinkling a bit of seed through it so he HAS to taste it? I find some birds are quite frustrating when it comes to fresh food but that's how I've been trying to get around it with seed junkies that don't want to know anything else
Let us know how you get on with him