Becky. Remove the blades again. The 'Felt' you speak of has a small hole in the middle which goes over a plastic pin to stop hair entering the cutter mechanism.
This same pin, is shaped the same as the hole in the centre of the upper blade.
The upper blade should be pressed onto this plastic pin, gently, until it is flush. This blade should have the teeth pointing downwards.
Then, attach the lower blade with the teeth facing upwards and tighten the two screws, until they grip but NOT TOO TIGHT.
Oil and hey presto!
davymac, July 2009