I have been using an HP 1525nw successfully in OSX for some time now.

When I tried to print this morning, suddenly, the OS cant see the printer. It is in the list (with a low toner warning) but all attempts to print to it result in a continuous search which never ends.

It may be relevant that I just upgraded to 10.9.3?

When I go to ADD PRINTER and let the OS search around, it finds my USB MX860 (and it's network version) immediately. But it doesn't seem to see the 1525?? If I leave it on for 5 minutes searching, and go off the WiFI router which is connected to the 1525, fleetingly, the OS Picks up the 1525 printer (and calls it a Bonjour printer, whatever that is) and then loses it within 2-10 seconds. If I leave the router connected, then after a few minutes, fleetingly, the OS Picks up the printer again, and then drops it almost immediately.

Meanwhile I can tell that the OS is scanning to see if there are any new printers on the computer because my MX860 (as well as the Network version) continue to refresh every 5 minutes. But when they do this, the 1525 doesn't re-appear.

(There are no error messages on the printer's display)

Does anyone recognise these symptoms please?