[Sussex] Curious Printing Problems x 2

[John D.]

Problem 1.

If I hit print on something for the Laser Printer (an HP LaserJet 5N) to 
"print" It usually tells me (via the dot matrix display) too load Letter 
(presumably the paper format). I have to hit "go" for it to print. Now 
I've managed to set the printer so it's set for A4 paper, but I'm 
wondering if my system has some sort of printing default set to letter 
format, and that the printer is looking for paper in that size (which I 
understand is the US equivalent of A4 anyway).

How would I check if something in the system needs changing?

Problem 2.

Same printer, if I print something that originally had some colour, I 
get the corresponding level of grey, except it's fading, as if there's 
not enough toner in it. But If I then do a "self test" the print is 
perfect (even if there's a "greyed" image in the self test). It it's 
just a straight text document i.e. letter or whatever the text is 
perfect, it's just areas of print that have been changed to "grey scale" 
instead of the files original colour.

Does anyone have any idea of what I'd need to check to find out why this is?

Cheers

John D.