Filter barely doing anything on Further's middle PU

[jerico]

The last day or two, I've noticed that the filter on my Further's middle pickup is very unresponsive - when turned all the way down, it is no where near as muddy as the neck and bridge pickup.  And when I turn the knob quickly, I can barely hear the wah effect that is very pronounced on the other 2 pickups.  I've only been noticing this the past day or so.
 
Any ideas what might be up here?
 
Thanks
 
Justin

[mica]

The middle filter on the Further is tuned slightly differently from the other two filters, so it should sound somewhat different.
 
Do I understand correctly that the sound was different before 2 days ago and that it has changed?

[jerico]

Hmmm. I'm not sure... It is definitely quite different from the other 2 though.  The rolloff (where I can hear the wah) seems very mild and very high - ie even when the filter is turned all the way down, it still sounds quite brite (this is with the pickup in the on position, not the brite position).  If it's normal, it's normal...
 
JC