2840 laser printer only prints on right side and nothing on left side

http://h30499.www3.hp.com/t5/Printers-LaserJet/HP-2840-prints-blank-pages-or-yellow-only/td-p/2326639#.Ur1kMH_lMgU

Other than tec guy are not advisable to do this exercise :Corosol align disturbed,open the printer up to corosol mechanism check rotary swing shaft left and right gears, there are markings which was exactly matching with rotary right & left disc markings. If its disturbed print quality issue will developed. If you have service manual read carefully before opening the printer.. Best of luck.

Other than tec guy are not advisable to do this exercise :Corosol align disturbed,open the printer up to corosol mechanism check rotary swing shaft left and right gears, there are markings which was exactly matching with rotary right & left disc markings. If its disturbed print quality issue will developed. If you have service manual read carefully before opening the printer.. Best of luck.

Corosol technology is older,slower sounds also too high, it is not suggestible to lubricate the moving parts because of cartrides will move while printing result lot of toner particles raises in printer chamber,if this particles deposited on lubricated area will abstract the moving spares. If you can do the periodical maintenance, use silicon grease for moving parts..

If you are a bit adventurous and a bit patient, you perhaps can fix this yourself, and not require any disassembling. It worked for me on a similar 'carousel' unit... hp2550L.

For extra info, check this post out. http://www . fixyourownprinter . com/forums/laser/40284 (remove spaces)

If you look closely at the spot where a toner cartridge slips into a slot of sorts, you might see left side aligned and right side just a little off of 'good alignment' for that slot. What I did is to pull on the top of the black-plastic gear. Pull it toward the center of the printer.

There is a small, white gear at the very top of the black gear (not easy to see at first). By this pulling and bending of the black-plastic gear, you can get the gear teeth free of the white gear --- for just a moment. Just enough for the gear teeth to free-up and find their proper place. It doesn't take much.

When done, take a breadth and relax. Turn power off/on, and try it out.

Take the toner cartridge out, shake it back and forth, and turn it around in a circle a few time. Put it back in the priter, and print. Order a new toner cartridge.

If this is an inkjet printer, ignore this response.

this is a typical problem.. this printer uses a carasol meaning that the toners are riding on a carasol there are 2 white gears that drive the carasol 1 on the right and one on the left. Half page fade is almost always a misaligned carousel! A Tech is needed or a service manual here is a link for the manual http://www.partshere.com/Models/Q3948A/CLJ_2820_Removal_replacement.pdf
look at figure 5-78 Removing the print-cartridge carousel you will see the white gears im talking about

I’m happy to help further over the phone at https://www.6ya.com/expert/ron_9356d26241d4cbf7

The problem is that the revolving drum doesn't contact the OPC drum proberly. You have to open the left side off the machine and replace the little white gear on the shaft that drive revolving drum. The gear has "jumped"one step and the revolving drum isn't parallell to the OPC drum. I fixed my 2840 last night it takes some time but now it works perfect.

It is the carousel that is dislocated. Check the alignment if it's brooken