Diagnosis
This is almost always an airflow or setup issue, not a broken pump. If the air isn't flowing properly over the cold coils, moisture can't condense.
How to Fix It
1) Check that the air filter is clean and seated correctly—a clogged filter is the #1 cause. 2) Make sure all the vents are open and nothing is blocking the front grille or top exhaust. 3) Verify it's in a closed space, like a bedroom or basement, not a wide-open area. It needs a contained space to lower the humidity.
If That Didn't Work
Listen closely. If the compressor is running (a low hum) but you don't feel cold air coming out of the exhaust, the refrigerant system might have a leak. That's a major repair.
Heads Up
Give it time. In a moderately humid room, it can take a few hours of runtime before you see a noticeable amount of water in the bucket. It's not instant.