Hi rmjk,
I understand you're having an issue with the photo tray on your Photosmart 6520 printer. I'm sorry to hear this has been happening but I will certainly do my best to assist you!
We will most likely need to do a reset on this unit to see if we can't get it functioning properly for you, but first I'd like to check if your printer as the most up to date firmware. To check this I'd like you to print a status report by following Step two: Print a Printer Status Report. Near the top of this page you will see Firmware Version followed by a long number. If that number is anything but PKM2CN1230AR then the firmware is not up to date and it would be best to update it.
If your printer is connected to your network you can attempt updating the firmware through the front panel. To do this, press the ePrint button (is across the top of your printer's touch screen on the far left) and then press Product Update and then Check for Product Update.
If your printer is connected via USB you can update the firmware on the computer, starting with clicking here. When the page opens, click the blue Next button and then scroll down looking for Firmware (1). There should be one update there for you to download and run.
Please let me know if this update was required and if it helped. If not, we will move on to the reset as our last option!