I haven't read through the entire thread but you could try hand feeding him. I do that with my 4 months old green tree frogs and they seem to enjoy it.
I also chuck in an extra one or 2 so they can hunt and have fun.

if you don't want to use your hand you could use tweezer/tongs but I've heard plenty of stories that it could hurt the frog but I've had no problems so far. Just use plastic not metal and hold the cricket in front of him
and have the tweezer pointing down so your hand is above. This will stop them from getting scratched or hurt.