The paper wont feed through tray 2...it seems like the "wheel" that feeds it through isnt picking it up. The tray is fully closed and there are only about 15 sheets in there.

common faults for poor feeding on lj5200
1, feed rollers are worn - replace
2, sep pad is worn ( cant seperate pages correctly)- replace
3, paper empty tray sensor actuator arm snapped - unable to raise cassettetray- replace arm
4. paper feed roller fail to turn- feed unit clutch assy faulty- replace feed asseembly
5.paper tray pass guide out of position (blocking feed path) - pin that holds in place has snapped- replace feed assembly

Usually that is caused by foreign object restricting the operation.
take the feeding tray out and open the top and examine it for foreign objects. It may need a little cleaning.

I have had this problem after printing a large batch of sheets on a heavy matte photo paper. The roller picks up a 'polish' from the surface coating and then fails to grip. I have tried cleaning the roller, with some sucess, but the best solution I have found is to feed through several blank sheets (just page throws in a Word document) of a ordinary 80 gram paper. Doing this between smaller batches of the photo printing seems to keep things flowing.

Check to see if the printer is actively trying to feed the paper. If you hear it trying to feed and see the wheels turning, but the paper won't feed, check to see if a screw securing the feed wheel has come loose. If you hear the sound, but nothing moves to pull the paper in, then you probably have a bad printer. They're too cheap to replace to bother fixing - so get a new one.

check tthe clips retaining teh feed rollers havent sliped off if it isnt picking up from tray take the tray at top out and then watch from above to see if the rollers are turning to feed paper.. if the lifts out check the side door guide isnt out of plavce check the end paper guides as well//check when you take the tray out look to see there is any paper stuck at the back where the tray sensors ares can cause a lift motor error aswell

Clean the feed roller.
Remove the paper tray, from the bottom there is a grey rubber semi wheel in the middle front of where the paper tray would be. Use a cloth with WD-40, brake cleaner, or lighter fluid to lightly wipe the rubber clean. Put the paper tray back in and it should print.

does the paper feed at all(1/2 way) no feed,if not pick-up paper most likely will be feed motor if 1/4,1/2 or 3/4 fed will be sensor at falt or 2nd tray conectors dirty or making false contact.

Feed the paper manually into the printer:
Place a sheet of plain A4 paper in the paper feed tray.
Move the paper support on the left-hand side to the left end of the paper.
Press the paper feed button.
If the paper does not feed, continue with step 2.

Check for any obstructions in the paper feed path:
Disconnect the cables from the back of the printer.
Open the front of the printer and check for anything that may be blocking the paper path.
Close the front lid and remove any paper from the paper feed tray.
Holding the printer in both hands, turn it upside down to see if anything falls out of the paper feed area. (Sometimes objects such as pens, paper clips and so on can fall into the paper feed area and cause blockages.)

Feed roller is dirty or worn thin, wipe rubber roller with damp cloth.

Is this a top feed - that is paper loaded on top at the back bottom feed from a tray underneath? Top feed take one sheet of paper and gently push it down whilst the printer is trying to grab it. Tray feed - take tray out make sure no paper fragments are in the tracks and find a nail board and gently abrade the pick up rollers.