False paper jam error on Epson Artisan 835 AIO printer?

My printer wont boot past a paper jam error. It's an Epson Artisan 835 - I have powered down, unplugged, checked every square inch for paper jam (nothing), cleaned print head rail, pickup rollers and moved print head to left side. Powered up and it seamed to be OK but up came the paper jam error again & again. I just added a CIS so I removed the cartridges and STILL get a paper jam error. This is getting old fast. I could use someones expertise here. Five stars to the person who's got the (correct) answer to this one!