Lanier 335c Paper is jamming in the middle of the machine with each print and keeps printing the same page

your web fell out, remove fuser,( lift handle on each side), take off web assy 2 screws 1 each side, rewind web and reinstall

I do not quite understand what you are saying. I think you mean that the carriage stops in the middle and it says paper jam after one page is printed. Look inside the machine and you will see a long chrome bar that the carriage runs along when printing. use some kitchen roll and clean any grease from the bar and try it again. If still have problem, does the 1st sheet fully eject from the machine or does its end still stay in the machine and then the error appears? I need to know the answer before can make more suggestions.

Make sure that all the paper trays have the correct size and direction (portrait or landscape) in both the copier and print driver.

These are your possibilities based on your error.

Front cover is open
Close the front cover of the printer.
Fuser cover is open
Close the fuser cover located behind the back cover of the printer.
Paper jam
Clear the paper jam. See Paper jams and how to clear them on page 85. If the printer
does not start printing, press the Go button.
Memory full
The printer memory is full and the printer cannot print full pages of a document. See
Solving print problems on page 97.
Print overrun
A print overrun occurred and the printer cannot print full pages of a document. See
Solving print problems on page 97.

http://www.brother-usa.com/ModelDocuments/Consumer/Software%20Users%20Manual/SUM_DCP_7030_7040_MFC_7340_7345N_7440N_7840W_EN_1650.PDF

here is the manual p4 and p16 discuss the topic:
Duplex printing 1
The supplied printer driver supports duplex printing.
Guidelines for printing on both sides of the paper 1
�� If the paper is thin, it may wrinkle.
�� If paper is curled, turn over the stack, straighten it and then put it back in the paper tray or the Manual Feed
Slot.
�� If the paper is not feeding properly, it may be curled. Remove the paper, straighten it and turn over the
stack.
�� When you use the manual duplex function, it is possible that there may be paper jams or poor print quality.
If there is a paper jam, see Paper jams in the User’s Guide. If you have a print quality problem, see
Improving the print quality in the User’s Guide.
Manual duplex printing 1
The machine prints all the even-numbered pages on one side of the paper first. Then, the Windows® driver
instructs you (with a pop-up message) to reinsert the paper. Before reinserting the paper, straighten it well,
or you may get a paper jam. Very thin or thick paper is not recommended.
Simultaneous scanning, printing and faxing 1
Your machine can print from your computer while sending or receiving a fax in memory, or while scanning a
document into the computer. Fax sending will not be stopped during PC printing. However, when the machine
is copying or receiving a fax on paper, it pauses the PC printing operation, and then continues printing when
copying or fax receiving has finished.


�� Manual Duplex
Check Manual Duplex. In this mode, the machine prints all the even numbered pages first. Then the
printer driver stops and shows the instructions required to re-install the paper. When you click OK the odd
numbered pages are printed. There are six types of manual duplex binding directions available for each
orientation.
�� Booklet Printing
When you want to print a booklet, use this function. To make the booklet, fold the printed pages down the
middle.
�� Binding Offset
If you check the Binding Offset option, you can also specify the offset for binding in inches or millimeters

which printer?

try this

1. Turn off the printer.
2. Remove any paper trays. Inspect them for wrinkled or damaged paper.
3. Also open the back cover of the printer if this model has one.
4. Open any other doors that give access to the printer's paper path and to the toner or ink cartridge.
5. If necessary, remove the toner or ink cartridge. Place it away from light/ sun light to avoid damaging it.
6. If you find a piece of jammed paper, remove it by holding it with both hands and pulling firmly. The goal is to keep the paper from tearing. If several pieces are jammed together, try pulling out the middle piece first to loosen the jam.
7. If the paper does tear, try rotating the roller gears manually to free the paper. Don't force anything, though. Do this step especially if the jam message comes up repeatedly without any obvious paper jam, there may be a small tear of paper inside.
8. Ones the printer is free of paper Replace the toner or ink cartridge and paper trays, close any doors you opened and turn the printer back on.
9. If the printer paper jam message still appears, then there is still some paper in the printer. Reinspect the paper path.
10. see alternative if the problem is still not solved.
    

alternative :
Load a piece of thick paper, for example photo paper and press the resume button (may be diffrent button on diffrent models) a few times to the printer picks up the paper and puts it through the machine.

Keep your paper feed under 15 pages. The paper will tend to pull to the right, but it will print correctly on the printed page. 20 to 25 pages in the feeder will result in a paper jam. To find the status on the print job, go to your control conter and hit printers. Choose your spicific printer and you may beable to save the printjob.

The document feeder on this machine uses a separation and a feed roller ,the pad is on the bottom and the roller sits on top . in most cases the pad will be white if it is not it must be cleaned .use isopropyl alcohol. then clean the roller using water on a paper towel. On the tray issue if the paper is torn or nicked the sensor flag may be damaged if it is you will need a service call . if the paper is not nicked check to see if the default paper size has been programmed into the user settings on the copier [ read the owners man.] When you send a print to the printer go to printing preferences and check on the paper size being sent to the printer it must match the paper size loaded into the machine

Sounds like you may need to replace the pick up rollers on the machine.  Without knowing exactly where the jam error happens during the print process, it's hard to say.