Xerox Phaser 8400. I am selecting Tray 1 (front

The printer trays accommodate most sizes and types of paper, transparencies, or other
specialty media. Follow these guidelines when loading paper and media in the trays:
- Envelopes, labels, and glossy paper can be printed from Tray 1 (MPT) only.
- Transparencies and custom size paper can be printed from Tray 1 (MPT) and Tray 2.
- Fan paper, transparencies, and labels prior to loading them in the tray.
- Use only paper envelopes. All envelopes should be printed single-sided only. Some
wrinkling and embossing may occur when printing envelopes.
- Do not overload the paper trays.
- Adjust the paper guides to fit the paper size.
- If excessive jams occur, use paper or other media from a new package.

I suffered from the same problem for a long time. We got Xerox Phaser 8550 and 8560 here. I choose on computer "tray 2" but the printer just print from tray 1 which is empty.

Today i figured it out! It's some configuration at the printer. So go to "Paper tray setp" -> "Tray 1 mode" and "Tray 2 mode" -> change to "static".

I figure it's like this. Before it was "dynamic", it probably means the printer decides it's better to use tray 1 even though you choose tray 2 - and this decision is stupid. Changing it to "static" fixes this.

Let me know whether this works for you too!

If you put Tray 2 in Tray 1's spot with the heavy stock in Tray 1 (now in tray 2's spot) and print from it, does the problem persist?

This may help...
http://www.support.xerox.com/support/phaser-7500/support/enus.html?objGUID=4538

Sounds like the maching rollers are just dirty and slipping on that paper.
I would open the paper path, and look for all the gray rollers. Use a 2 step process to clean them. First use something like Fantastic, or formula 409, a stronger soapy cleaner to clean all those rollers, then clean them a second time with rubbing alchol.
One will clean off paper dust, general dirt the other will break down ink and oils that may also be on the rollers. You may want to clean them 2 or 3 times if it has never been done.

I am going to assume something here. That the paper does get out of the tray just an inch or 2 correct?
If so, the registration clutch is bad, it is really common.
You can do one of two things. If you go onto the Xerox.com site you can find the parts list for the machine and get the part number.
If the machine is feeding the paper out of the trays just a couple of inches and stops, you can call 1-800-835-6100 and follow the prompts to order parts. Tell them you want a registration clutch for a Phaser 8400 and they will look it up and send it to you.
If so. Just E-mail me at [email protected] and I will send you directions on how to change it. It really is an easy clutch to replace. Even if you never have changed one, I would doubt it would take a half an hour to change start to finish.

Where does it jam? Is it making an "accordion fold"just before it enters the front rollers? Does it pick up a second sheet from the tray in the process?
Does it print OK from the manual feed tray?
If so, there might be a sensor worn out at paper entry, near the entry rollers and the plastic curved flap in the front. Once had this problem, the sensor's plastic "tongue" was half it's usual size, worn out by the paper abrasion alone.

From the start menue to printers and faxes go to your printer right click and select properties label the 4 drawers as to paper type and select continue, or auto continue to off.
-Carl, please let me know if this helps.

Here is the Xerox support page for your printer. It even has a movie on removing paper jams.
http://www.office.xerox.com/perl-bin/product.pl?page=sprt&product=8400&country=United%20States&language=en#_manuals_and_documentation_

The manual bypass tray on the Phaser 8400 can be set only when you have paper in the tray.

The envelope will read in the set up when you have it in the tray.

Here ya go...

Tray 1: (standard) 16 lb. Bond – 80 lb. Cover (60 – 220 gsm), coated, Phaser High Resolution Photo Paper, labels, envelopes, business cards, Phaser Professional Solid Ink Transparencies, Phaser Weatherproof Paper, Phaser Postcards, Phaser Trifold Brochures. Media sizes: A/Letter, Legal, Executive, Statement, US Folio, A4, A5, A6, B5 JIS, B5 ISO, 3 5 in. Index Cards, custom sizes; Envelopes: #10 Commercial, DL, C5, #5 , #6 , Monarch, Booklet, Lee (A7), Choukei 3 Gou, Choukei 4 Gou, custom.
Tray 2: 525-sheet tray (standard) 16 lb. Bond – 28 lb. Cover (60 –122 gsm), coated, Phaser High Resolution Photo Paper, labels, envelopes, Phaser Professional Solid Ink Transparencies, Phaser Weatherproof Paper, Phaser Postcards,Phaser Trifold Brochures. Media sizes: A/Letter, Legal, Executive, Statement, US Folio, A4, B5 JIS, B5 ISO; Envelopes: #10 Commercial, DL, and C5.
Tray 3: 525-sheet Feeder (standard on DX) Same media weights and sizes as Tray 2.
Tray 4: 525-sheet Feeder (optional) Same media weights and sizes as Tray 2.