Epson Artisan 837 - Clicking sound from paper tray when printing

When the printer starts to print, the paper tray is extended just a bit and a "clicking" sound is heard. It sounds like a gear is not fully meshed. Then there is a error message advising a paper jam. However there is no paper jam. If I hold my thumb hard against the paper tray on the right side to keep it from being pushed outward and keep it tight into the printer, all is OK and the printer prints as it should. This pertains to both the plain paper as well as the photo paper. I'm wondering if it is the paper tray or something else?

Thanks in advance for any replys.