Yes this is for paraffin heaters.
When you say you trim the wick. what you do is to remove Excess carbon from
it. most heaters come with a gadget to use so that you keep the wick level
after trimming. otherwise turn it down till it is just about level with the
rim , remove the centre fitting then run your finger around the wick just
to remove the excess carbon, replace the centre and you should be ready to
go.
My thought is.How old is the heater?
If its bought as new then why not contact the manufacturer , could just be
a faulty heater. though I have never heard of one.
If you know the make you could still contact the maker for advise.

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David Hill
Abacus Nurseries
www.abacus-nurseries.co.uk