I bought my Phantom 2 Vision a year ago and have the Model PVT581 transmitter WITHOUT the mini USB port connection. It has been several months since I've flown my Phantom, and when I took it out to fly yesterday (after upgrading to the latest firmware) it was operating a little erratically, so I thought I'd calibrate the transmitter. I downloaded the latest Assistant software (3.6). My problem is: I can't figure out how to connect the transmitter to the computer to calibrate it! The user guide is next to worthless in offering an explanation and everything I've found on YouTube have transmitters with the mini USB connection at the bottom. I DID find a post on YouTube that showed where there was a mini USB connection on one of the internal circuit boards, but when I tried that connection (after opening up the transmitter) the Assistant software did not recognize the transmitter, even though my PC indicated that it had recognized new hardware. I tried calling customer support yesterday, but getting through to a technician is about as likely as hitting the Powerball… It seems like I had calibrated my transmitter a year ago when I first bought the Phantom. I just can't remember how in the world it was accomplished. Thanks in advance for your help.