As your in a manual give the tail a little kick with out pushing the whole tail down, that will give you a better pop out of manuals and after that just remember to slide your front foot out to level the board

I do slide my foot I have trouble with the popping when I'm in a manual but thanks I'll give it a try

I'm definitively really late but an answer to your question would be, to let go a bit of the manual (to have more action when kicking against the pop). So my suggestion is that: let go a bit of your manual, then kick hard and balance your ollie.