I have been printing checks without problems for years. I had the printer (only) turned off for a few days. Now I get an error message on a PRINTERS FOLDER window that says:

There was an error writing to LPT 1 for the printer (Epson LQ-200):
The printer is not ready. Make sure it is turned on and online.
To continue printing, click retry.

Retry does nothing.
The printer lights are on and it is online.
I tried turning the computer off and restarting. It did nothing.

The cable connecting the computer to the printer is solidly inserted.

I checked Printer Properties. the custom defined size is 850 X 700... nothing has changed here. In FN under Print checks the Printer is set to "always use this printer."

The check form settings are unchanged and are the ones listed by John in response to Tim Nihoul's check print inquiry.

The font is also unchanged, Courier New, size 12 char/in.

FN prints reports on my other printer just fine.

FN will print the check on blank paper in question on my other printer. However, when I change the printer back to the check printer I get the same problem.

Check Form Navigator printing

It states:
From the work station, select
Start | Settings | Printers.
Right click on the printer and select Properties.
On the Details tab, select Capture Printer Port.
Set the Device: to the port set when CFN was installed such as LPT1.
Set the Path: to the network printer.
Be sure to check the option to
[x] Reconnect at logon. So the settings will be remember when the workstation is restarted.

I did not find the
[x] Reconnect at logon.
Is that because I have a single computer, not a network?

Try running a printer test. Start | Setting |Printers. Right click on the printer and select Properties. Select Print Test Page.

If this test page does not print then follow the parrallel printer cable from the computer to the printer.
Do you have an external zip drive? Is it turned off? If so then turn it on. The printer cable goes thru the zip drive. If the zip drive is not on then it will not pass onto the printer.