Glen Heater - Model 2142

[brocher]

I have a low heat Glen Heater Model 2142 in my small airing cupboard. It's been there now for about 12 years. Recently, it seems not to be pushing out as much heat as before but this may be imagination. I have just cleaned some dust off it and checked that it isn't leaking or anything and all seems to be OK. Does anyone have any thoughts? Thanks