Lowered GENTLY ≠ energy conserved
Mass lowered gently to equilibrium (extension e): GPE lost = mge, but EPE gained = ½ke² = ½mge — exactly half. The other half went into the hand (external force did negative work). Classic "explain why the two answers differ" 2-marker: the mass was not in free fall; an external force removed energy.
What this actually means
Lower a mass gently to its equilibrium extension e: the mass loses GPE = mge, but the spring stores only ½ke², which works out to exactly half of that. Half the energy has apparently vanished.
It went into your hand. Lowering gently means an external upward force acted throughout the descent, doing negative work on the mass and carrying energy away.
The examiner phrases it as 'explain why the two answers differ'. Answer: the mass was not in free fall; an external force removed energy. Two sentences, two marks.