A stalled gold line almost always comes down to one of five causes, and every one of them traces back to an official game mechanic - not bad luck. Work down this list in order and you will find the break in your line.
When Gold stops, run through the five causes below in order. Each pairs the failing sign with the mechanic behind it and the fix that targets that mechanic.
Symptom: the machine sits idle while Sand piles on top. Mechanic: the Shaker processes Wet Sand only. Fix: route water into the supply before it reaches the machines - 1 Sand plus 1 Water becomes 2 Wet Sand, so the water step also doubles your material.
Symptom: throughput dies even though Wet Sand keeps arriving. Mechanic: Gold is the only solid that passes through the machine body; anything else lodges inside. Fix: dig the stuck pixel out by hand and keep foreign material off the line from then on.
Symptom: the leftover material (called Residue here and "Slag" in some guides) stacks higher and higher. Mechanic: one Shaker sheds its Residue painfully slowly. Fix: slope several Shakers into a descending staircase so gravity keeps the tops clear.
Symptom: the line works, but Gold appears in dribs and drabs. Mechanic: each Wet Sand pixel has a 1-in-4 chance of Gold, so a small batch can legitimately produce nothing. Fix: keep feeding - roughly 4 Sand per Gold end to end is normal, not a fault.
Symptom: Sand stops darkening into Wet Sand. Mechanic: a water droplet that does not settle within 45 seconds evaporates, and liquid escapes through gaps where block corners meet. Fix: store water in a basin with sealed diagonal joints instead of letting it run loose across flat ground.
Burnt Residue that lands on the Press and just sits there means the drop is too short: the machine needs 25 or more blocks of falling distance before it converts anything. Build the tower taller, and use angled Launchers to sweep away anything that still refuses to convert.
If more than one cause applies, the fastest path is usually rebuilding the line with the tutorial's checkpoints rather than patching it in place.
Dig, wet, slope, feed, harvest - each step ends with a checkpoint so you can verify the mechanic is working before building the next one on top of it.
Ratios, the pass-through rule, and the physics that make the diagonal staircase the default layout.
Once Gold flows again, these are the habits that stop the same five causes from creeping back in as your factory grows.
Many jams start as a logistics mistake - a blocked belt bottom pixel or a missing Launcher. The logistics guide covers the three movers and their rules.