A small duck sometimes comes off the bed with a peg that will not seat, a hat that will not click, or support that has welded itself to the bill. Force is how bills snap. Work from the least destructive step.
This is general advice for FDM parts. It is not a claim that Duck Heroes models use pegs or moving joints. If a future file includes a separate part, the same care applies.
Supports first
Score the contact point with a sharp blade held flat, not stabbed inward. Warm the support gently with a hair dryer if the plastic is PLA and the room is cold. Pull along the surface, not away from a thin edge. If plastic tears out of the bill, stop and print the next one with a larger support gap.
Pegs and press fits
If two parts are meant to join and they do not, do not clamp them in a vise. Check elephant foot on the peg and on the hole. A bulged first layer makes both sides wrong. Trim the bulge with a knife, then try again. Preventing elephant foot saves you from doing this on every copy.
A little dry fitting, then a pause, is safer than sanding a hole wider than the design. If you sand, mark the high spot and take only that.
Stiff but not broken
Layer bonding can make a thin costume piece feel rigid and brittle. That is not something you “loosen” by bending it back and forth. Bending is how it snaps. Reprint with slightly more temperature or slightly less cooling if layers are separating. Reprint with more cooling if the shape slumped.
Paint and glue
If you added a magnet or a pin, a tight hole plus glue is permanent. Test the fit before the glue. A drop of cyanoacrylate is not a substitute for a part that was printed oversized.
When to reprint
If the eye is damaged or the bill is torn, reprint. A repaired face is what buyers notice. Save the profile change in the slicer so the next copy does not repeat it. The inspection list in the first print is the right moment to catch this, before you have a row of identical problems.