Bosch Exxcel 7 WTW863S1GB Tumble Drier not Drying

[samuelodog]

Hi - Bosch Exxcel 7 WTW863S1GB - condenser:

my tumble dryer has started to refuse to dry clothes. Recently moved it into the bathroom, in a tight corner, but beside window. On a normal dry cycle, it takes c. 30 mins then filter clean lights up, loads of damp fluff stuck all over filter and door. I clean it, start again, half an hour later - the same. its taking c. 7 hours to dry a normal load, with intermittent cleaning of filter in between. I clean it thoroughly, taking out both bits and emptying loads of fluff. I havent changed what I wash or how I wash it, so its not the clothes, its the drier.

so: Is it the bathroom damp doing this?
Is it a fault with the machine?
Why is so much wet fluff coming out?
What can I try other than cleaning the filter again and again?!

many thanks!

Sam