The same piece that presses easily on one guzheng can feel immovable on another. That is not imagination and not a weak hand: feel is the sum of a few things you can see and adjust.
The test is whether the note arrives. Pressed notes on a guzheng have to reach a semitone, a whole tone, sometimes a minor third. If the string bottoms out under your finger and the pitch is still short, the action is high or the string is stiff. If it overshoots at a touch, the action is low and hard playing will slap. Repeat on the same note rather than trusting a general impression.
Action should change gradually. Bass strings are thicker and swing wider, so they sit a little higher; treble strings sit lower. Press from the bass end to the treble end: a section that suddenly rises or falls usually means uneven bridges or a nut problem, not a characteristic of the instrument.
A glissando that catches has two usual causes. Action too high, so the finger cannot press to the board and the slide breaks; or a pick edge that is too thick or too pointed and scrapes along the string. Try the same passage with a thinner pick to separate the two (choosing picks).
What you can adjust and what you should not. Moving a bridge changes the speaking length and tension, and with them the feel — the easiest thing to change yourself. Nut height is structural; do not shave it. Old strings lose tension and feel soft; a new set restores it (strings).
Small hands. A pressed note has to be pushed past the bridge, and a small hand that cannot reach ends up jabbing with the fingertip, which makes a good instrument feel bad. A shorter instrument or a lower action suits these players better than more force (choosing a size).
Testing in a shop. Bring a piece you know, press the notes you actually use, glide, then try a tremolo. When two instruments at the same price feel very different, check whether the action matches before blaming the instrument (inspecting a guzheng). Feel can be compared; do not accept “it will loosen up”.
If the feel does not suit you, work out whether it is action, picks or string condition first — most cases do not need a new instrument. How to weigh this when buying is in the buying guide. If you are unsure, tell us which notes you cannot press.