Night Storage Heater Making Eyes Sting

[renegadefm]

My elderly neighbour asked me round to look at her night storage heater in her front room because although its working and giving out heat, she said this winter its been making her eyes sting. 

She has an exact same heater in a different room and that doesn't make her eyes sting, which would suggest the other heater is definitely faulty in some way. 

Does she need a new heater, or can these be serviced? 

[The Builder]

This is an odd one. My first thought is that something has fallen in through the grill at the top where the hot air comes out.

Whatever it is, it would fall directly onto the elements and is taking its time about burning off.

I suppose it's possible that wiring is overheating inside. Plastic cable insulation will make your eyes sting while it burns off. If that's the case, I guess the whole unit will fail before long.