Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Plastic light cover fell off on first refill

This is a nice humidifier, with cool vapor coming out the smoke stack and a light to make the train glow at night, like a big night light. However, to make the train light up, a blue light bulb protrudes up into the water reservoir, protected by a small transparent cap that is part of the reservoir itself. That cap is simply press fitted into the water reservoir - from the inside! The cap fell out on the first refill and is very difficult to get back in position - one has to rattle it around, balance it on the end of a pencil inserted through the hole and lower it back into the hole. That done, the fit is so loose that it just falls out again. Some glue might fix it, but for now we have an expensive night light.