Checking the correction operation of a tumbler drier

We have a domestic Zannusi condensing tumbler drier. It heats OK and dries clothes OK – but it also puts out quite a lot of damp air.

Is there a way to check it’s efficiency / correct operation? We’ve checked / cleaned the filter and emptied the condensate tank, but still it feels (in the kitchen) as if it’s putting out more damp air than it should. Certainly more than it used to!

Any ideas for checking it out would be welcome.

Thanks