Printing problem

[Jack Jackson]

Hi,
I'm getting a printing error when I print to my network printer that 
only occurs with Firefox. It's complaining that the Postscript 
interpreter in my printer is too old  (2014.108 and should be >2015)

However the proposed solution:

gs -q -sDEVICE=pswrite -s OutputFile=- -dNOPAUSE -dBATCH 
-dMozConvertedToLevel2=true - | lpr [options]

(or specifically in my case:

gs -q -sDEVICE=pswrite -s OutputFile=- -dNOPAUSE -dBATCH 
-dMozConvertedToLevel2=true - | lpr 
${MOZ_PRINTER_NAME:+'-P'}${MOZ_PRINTER_NAME}

)

does not work at all. If I set it to ConvertedToLevel2=true I get 
gibberish; if to level 1 I get a blank page.

Can anyone offer any assistance?

Thanks in advance