Had an awesome bonding moment with my sun conure... was covering his cage for the night and he came to a specific corner where we play peek a boo... not only did he want to play but he also let me tickle his tummy and was making all kinds of happy sounds and movements... this is big because he still isn't very trusting and doesn't like to be handled... so for him to let me rub his tummy is really awesome... i know playing at bedtime isn't the best idea but with this guy I will take any small win I can get.
Awww, he's coming around! Good for you and better still for your bird! Patience, persistence, consistency and love always do the trick in the long run. Now, a word of caution, bellies are a no-touch zone so don't tickle there too often.
Try caressing the sides of his beak with your fingers. Use your index and thumb as if you were going to 'pinch' it but just caress it from the base to the tip. Parrot parents do this to their babies when they are very young to 'activate' the feeding response and it's something they all like to the point that even the ones that don't like to be touched anywhere else will allow you to do it (it's also a great bonding tool).