A network printer attached to an Airport Extreme router has "disappeared"

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I have an Airport Extreme network with 2 Airport Extreme routers, 1 attached via ethernet to the network (wall) and 1 extending the network. I have 2 printers (HP LaserJet P2015dn), 1 connected to the main Airport router and 1 connected to the extender Airport router. After working fine for months, the printer on the extender Airport router has stopped printing. The print utility is greyed out which usually means something is majorly wrong. The other printer was working fine, but when I started working on the extender printer, it went offline, too. I reset the network card on each of them, but it only got the printer on the main router to go back online. I am using 40 MacBooks (2.1 GHz Intel Core 2 Duo; 2 GB RAM) running OS X 10.5.6. Like I mentioned earlier, both printers were working fine for months, up until a couple of days ago. Any help would be greatly appreciated.