Major volume drop on Strat middle pickup

[Simon D]

The middle pickup on my Strat is giving a huge drop in volume compared to the neck and bridge pickups. The problem is magnified when the bridge/middle tone control is turned to 0. When played clean at bedroom volume, switching to the middle pickup renders the guitar almost inaudible, on the drive channel it cuts the gain in half. The guitar has been checked out by a tech, who checked the wiring for dry joints and cleaned the switch, but the problem remains.

Does anyone have any idea what could be causing this - could it be a faulty pickup, perhaps?

BTW,  the guitar is a Fender US Series Strat, which I've owned from new since the summer.

Any help gratefully received, thanks guys.

[Philly Q]

Don't know really, but if you have a multimeter you could try reading the pickup's DC resistance.  If it's much less than, say, 5 or 6K it would indicate some kind of short in the coil, I guess.

[lifted]

What's a Dry Solder joint? I just read that in another post

[Elliot]

A dry solder joint is where the soldered part (say a wire) no longer conducts with the other part (say a potentiometer) - so there is no electrical connection.  It can sometimes be spotted by the solder looking dull and grey, but not always.  Its easily fixed (by re-soldering) but not so easy to find in complicated electronics (which guitars aint.)