One of my most memorable contest tow radio call between a ballasted glider and the tow plane:

Glider: "Five more knots color & Type tow plane"
Tow plane: "If I speed up any more we are not going to climb"
Glider: "If you don't speed up, we are both going to die"

The second call from the glider had a good bit of heat behind it. If it don't feel right ask for more speed. Speed and Altitude are your true friends, the rest can't be counted on when the going gets tough.