Paper tray missing but is it still usable?

First, when you put the paper in the tray make sure the paper holders on the side and back of the tray are positioned against the paper stack but not so much as to be snug.
Next, inside the compartment where the paper try is inserted look for a small plastic piece that hangs below the ceiling of the compartment. It should be near the front of the compartment hanging down and should swing freely backward.
Also, in the printer's paper tray settings make sure that tray is set to that size of paper you are using.

The printer should accept print paper ready for feed commands when computer sends jobs with clicks. A paper feeder tray may be clogged, attempt to open compartments to ascertain for misaligned or adjusted entrapment areas. Paper feeder adjustments that are tightened least allows feeder processing while loosened paper feeder clips allows several print papers at a time. Select the appropriate adjustment for the papers. Second, printers that run out of ink display sensitive malfunctions either as inability to feed paper when available. Ascertain that printer ink is available.

You sent a paper size different of the requested by the printer. Just load the requested size or delete the spool.
Some PDF downloaded from internet has A4 or 8,5x11", maybe is requesting one of this sizes.

If you can not delete this message, delete the spool using the printer manual in the control panel of the printer.

The paper tray itself is probably missing a small peice. Look towards the front of the tray... there is a guide (about 2" wide) that, if you push down, it springs back and forth. My tray was missing a small peice of flat metal that popped off. The feed roller rests on this piece when the tray is loaded. If the piece is missing, then the roller is to close and the paper cannot make it through into the printer. Still looking for the part number....

please chack it feed claught unite
thanks

There are two possible solutions: The first is that the lugs on the side of the paper tray are broken, and the printer cannot "see" a paper tray. In this case you need a new paper tray. The other possibility is that the tray and paper size sensor inside the printer is faulty. Often just pushing the contacts can free them, and sometimes the metal prongs that sense the lugs on the side of the paper tray get unseated. Just use your finger to reseat them correctly. If that doesn't work, the sensor board is likely to have failed, and will need replacing

Tektronix printer paper trays, I seem to recall that there's a plastic key that fits on the right side of the paper tray. It's a little plastic piece that just clips in on the right side of the paper tray. Sounds like it's missing

Fixing paper feed problems

• Ifthe printer is not picking up paper, check to see if there is paper inthe IN tray. If there is not, load paper into the IN tray and press the RESUME button.
• Do not load more than 100 sheets of 20-pound paper in the IN tray. The paper stack should not exceed 10 mm or .38 inches.
• Use the same type paper in the paper tray when you are printing.
• Makesure that the paper width adjuster is against the left side of thestack but is not blocking the stack. Push in the paper length adjusterto make sure that the paper is fully seated in the printer. Do not pushso hard that the paper buckles.
• Do not use paper, envelopes, or cards that are torn, buckled, have curled edges, or do not lie flat.
• Ifusing the IN tray to load several envelopes, push the paper lengthadjuster toward the envelopes until it stops. Do not bend the envelopes.
• Load only one envelope at a time in the single-sheet input tray and be sure that it is inserted fully into the slot.
• Use envelopes with square flaps instead of triangular flaps, or tuck the flaps inside the envelopes.
• Ifthe printer's paper feed rollers become covered with debris (dust orpaper fibers), clean the rollers with a soft cloth dampened with water.
• Ifthe paper loads unevenly in the printer, one or more of the rollers onthe rear access door is missing. Remove the rear access door and checkto see if all six rollers in the door are present. If any are missing,the door assembly needs to be replaced. This is a customer replaceablepart, number C4557-60076.
• Ifthe printer does not drop any paper from the wings to the OUT tray,remove the excess paper. The paper stack should not exceed 10 mm or .38inches.
• Ifthe printer is sending more than a single sheet through at one time,remove the paper from the IN tray and separate any sheets that arestuck together. Reload the paper in the IN tray.
• Ifthe printer is not ejecting paper, then turn off the printer. If yourcomputer is turned on, turn it off. Then, turn on the computer. Wait afew seconds. Turn on the printer.
  NOTE: If you continue to experience paper feed problems, try other media or paper types. Refer to the User's Manual for supported media types and specifications.

Error Code 6001 ~ 6999 are simply service required errors and are very general. I would imagine that if the tray is missing the printer will produce a fault. For starters it will think it has no paper and therefore will not try to pick up paper from the tray. If the tray is opened during operation I believe the printer stops, therefore there must be a sensor for the tray - no tray means sensor is operated. Best guess - fit a tray.