OK, here's what I understand so far, and the suggestions I have (just want to be sure we're on the same page):
-The model is a 4100N. I'm slightly puzzled by this because you mentioned a Tray 2 and a Tray 3 in your original post. The N comes with 2 trays, a Tray 1 (fold-out tray) and a Tray 2 (slide out tray). It's the 4100TN that comes stock with an additional slide out tray (Tray 3). I'm assuming you added an optional tray after you bought to get to 3 trays total. No big deal on your problem though.
-You prefer to use the control panel to make adjustments. I'm the reverse, so I'll dig in to the manual for instructions. Note that I'll post a link to the manual at the bottom of this reply in case you don't have one. I'm going to concentrate on what I think are your key issues here. The manual will discuss something then direct you to another page for details. If I tried to post all those referrals, this reply would be enormous. Note that the page numbers given are the page numbers within the document (in other words, HP's page numbers) rather than the page numbers of the downloaded .pdf file.
-On the affected 4100N, Tray 1 mode is cassette. This shouldn't have any affect that I can think of on a job sent specifically to Tray 1. But I'm also puzzled by your statement that "if i use First it will print from Tray2 or 3". That's the reverse of what I think it's behavior should be.
-You get the 41.3 unexpected paper size error AFTER you print on the cardstock rather than before. That puzzles me too. Usually I see these BEFORE a print job prints when the job specifies a paper size or type in a tray different from what the printer's been told it has in that tray.
-You've tried setting the Tray 1 size to custom. Note that you also need to define the custom size and the margins (this is why I was asking for the size of the cardstock). "Tray 1: ...If custom paper is loaded, set the size of custom paper from the Printing Menu to match the paper loaded in tray 1 (you may also need to set the type. I think you've been using plain? It may need to be set to cardstock if these are indeed cardstock). To print custom-size paper, see Guidelines for printing custom-size paperâ on page 63."
Page 63 says "Guidelines for printing custom-size paper
Do not attempt to print on paper smaller than 76 mm (3 in) wide
or 127 mm (5 in) long.
In the software application, set page margins at least 4.23 mm
(0.17 in) away from the edges.
Feed short-edge first.
Setting custom paper sizes
When custom paper is loaded, size settings need to be selected from
the software application (the preferred method), the printer driver, and
the printer control panel. Settings in the printer driver and software application override control panel settings. (Software application settings generally override printer driver settings.)
If the settings are not available from the software, set the custom
paper size from the control panel:
1 From the Printing Menu set CONFIGURE CUSTOM PAPER=YES.
2 From the Printing Menu, select inches or millimeters as the unit of
3 From the Printing Menu, set the X dimension (the front edge of
the paper) as shown in the figure above. The X dimension can be
76 to 216 mm (3 to 8.5 in).
4 Set the Y dimension (the side edge of the paper) as shown in the
figure above. The Y dimension can be 127 to 356 mm (5 to 14 in).
For example, if the custom paper is 203 by 254 mm (8 by 10 in),
set X=203 mm and Y=254.
5 If custom paper is loaded into tray 1, set TRAY 1 MODE=CASSETTE
and then set TRAY 1 SIZE=CUSTOM from the Paper Handling
Menu in the printer control panel. See âCustomizing tray 1
operationâ on page 69."
Page 69 says (everything leads somewhere else) "Customizing tray 1 operation
The printer can be set to print from tray 1 as long as it is loaded, or to
print only from tray 1 if the type of paper loaded is specifically requested. Set TRAY 1 MODE=FIRST or TRAY 1 MODE=CASSETTE in the Paper Handling Menu at the printer control panel (see âPaper Handling Menuâ on page 210).
TRAY 1 MODE=FIRST
Means that the printer usually pulls paper from tray 1 first unless it is empty or closed. If you do not keep paper in tray 1 all the time, or you use tray 1
only for manually feeding paper, keep the default setting of TRAY 1 MODE=FIRST in the Paper Handling Menu.
TRAY 1 MODE=CASSETTE
Means that the printer treats tray 1 like trays 2, 3,and 4. Instead of looking for paper in tray 1 first, the printer pulls paper from the tray that matches type and size settings selected from the software. When TRAY 1 MODE=CASSETTE is set, an option appears in the Paper Handling Menu to configure size as well as type settings for tray 1. Through the printer driver, you can select paper
from any tray (including tray 1) by type, size, or source. To print by type and size of paper, see âPrinting by type and size of paper (locking trays)â
on page 70.
As I said, I'm not going to try to follow all the page referrals, and I don't think I'm really helping you much so far. Wish I had a "magic answer" for you.
I think it's going to be a bit of a "slog" for you finding the right combination of settings to make this work. For what it's worth, I've usually been able to find the answers by digging through the manual, but I hate doing that and prefer the experiment first. Manual's a last resort for me, but you might have to use it.
At least I have one definite answer for you. You mentioned that "The thing that is different on the troublesome 4100N and other 4100N is that this one gives me the option of changing the Paper Type and Paper Size while the other printers do not." As per above "When TRAY 1 MODE=CASSETTE is set, an option appears in the Paper Handling Menu to configure size as well as type settings for tray 1."
Just so you know, I'm not abandoning you by suggesting the manual. I just don't have one of these here any longer to experiment on (we upgraded to 4350dtn printers from our old 4100's). I'm largely going by memory of 3 years of maintaining them. I'll be glad to give further feedback to the extent that I can.
Here's the link to the manual. The one you want is the "HP LaserJet 4100 Series - User Guide"