Jam light always on

Hi,

Jam light is always on, and i cant print

i have open every single port and tray and there is no sign of paper jam...

i have pressed the test switch, below the formatter card and printed one page with horizontal lines (engine test) ... that means that i have to change the formatter card?

any other way? because it's an old printer and the formatter card is too expensive.

this is where i find out about the test switch: http://www.laserpros.com/tech_tip_p2015....