The best ear cleaner I have found is called EPI-OTIC.  It is available from
vets and also through some pet stores and online pet suppliers.
 
Epi-otic is a foaming ear cleaner that my previous vet recommended as safe
for all animals.  Basically, you drop a couple drops in each ear, "swish"
the ferrets ear around (grabbing the cheek and moving while listening to it
"swish") then the foam pushes the particles out.  You would take a q-tip
and clean around the outside and partly in the ear.  It is great ear
cleanser for those who are scared of damaging ear drums, etc... I recommend
it especially for those who are "first-timers".  Some vets do not suggest
using q-tips, others do, it is personal preference.
 
I have suggested to theferretstore.com that they start carrying it.  Start
with your vet, they will know where to find it.  It is not any more
expensive than any other ear cleaner and your ferrets will be much happier
as a result.
 
Good luck!
[Posted in FML issue 2832]