dyson dc04 over heating?

Our DC04 smelt of burning and I replaced the motor with a known working 2nd hand one from a dc07 which i'm told is compatible.
I also replaced the post filter and hepa filter at the same time, but with non genuine filters.
The new motor worked fine, no burning etc and picked up fine, however after about 20 minutes of use it cuts out (main hoover feels warm) so I presume it's over heating and the thermal cutout is activating.
I washed the new filters (And stupidly washed the hepa filter too) and now the hoover cuts out after about 5 minutes of use.
My question is, can the non genuine hepa filter be over heating the motor, it's clearly worse since washing it?
cheers

Robert
May 2010