If you received an encoder w/ unsoldered pins (I assume you mean the Hamamatsu pins), then that wasn't Trossen Robotics fault, but ours...

I'll refund you the price for that one ecoder module, as it should work correctly.

The onboard Hamamatsu P5587 sensors are no longer made, and we're looking for a replacement sensor.  Out of every 8-10 boards we make, there's always one that fails the test.   So, we do test the boards before they ship.  Now, I'm guessing the one you received tested out okay, because even unsoldered, the encoders can work if all pins are in contact w/ the pads.

Best Regards!