Our service source disks are packed away. I tried searching through the Apple Knowledge base here:
and ran out of time. You may want to look and I will try back.
Double check for paper jams first.
I looked at the LW Service Manual and didn't find the condition you described. There's nothing about the two LEDs flashing. Here's what the manual says:
The printer has three status LEDs: Ready/In Use, Paper-
Out, and Paper-Jam.
While on standby, the printer's Ready/In Use status LED
glows steadily. When a print command is received, the fan
comes on and the Ready/In Use LED flashes.
If the cassette tray is empty and the printer is set for
cassette feed, the Paper-Out LED glows steadily.
If paper is jammed in the printer, the Paper- Jam LED