If I can't intubate I try a smaller 24fr if that doesn't work I use a small naso gastric tube it's long and flexible then feed a medina over the top as the bottom hole allows the smaller tube to slip through and always use plenty k.y. If that fails then I use a stiff tube and have to push against the resistence a bit more firmly. Breathing in deep while inserting and out slowly while trying to push in.