I love the new psy system because with the old one increasing the chance of a psy power and also its effect was too much.
it was easier for a psyker to hit with a power than for a fighter to hit with a weapon.
Now is more balanced and to increase the chance the psyker must draw less power from the warp.
Fair.
As many said the problem now is the push rule.
Hot to solve it? simple.
Push add +2 (or more) to the psyker psy power not to the power level.
so pushing rise the chance of "casting a spell" (sorry I'v been rised with bread and D&D) instead of decreasing it but at the increased risk of Psychic Phenomena or worse....