My Canon printer Pixma MP510 won't print and is giving the following error indication - Auto sheet feeder - there is no paper; however there is paper and when I press OK it keeps giving the same error.

From Canon Help Files.

Automatic Print Head alignment failed
Possible causes are as follows:
A4 or Letter-sized paper is not loaded on the Auto Sheet Feeder.
Press the RESUME/CANCEL button on the printer to clear the error, then load one sheet of A4 or Letter-sized paper in the Auto Sheet Feeder.
Automatic print head alignment cannot be performed using paper from the Cassette. For automatic print head alignment, always load paper in the Auto Sheet Feeder.

Print Head nozzles are clogged.
Press the RESUME/CANCEL button on the printer to clear the error, and then print out the nozzle check pattern to examine the print head condition.

For information on how to print a nozzle check pattern, see "Printing the Nozzle Check Pattern."

The Paper Output Slot has been exposed to a strong light source preventing correct Print Head alignment.
Press the RESUME/CANCEL button to clear the error and move the printer to a darker location.
After carrying out the above measures, if the problem continues after aligning the Print Head again, press the RESUME/CANCEL button to clear the error, and then perform manual print head alignment. For details on manual print head alignment, see "Manual Print Head Alignment."

Envelopes must be fed from the Auto Sheet Feeder. Use either European DL or US Comm. Env. #10-sized envelope.
Important :

• You need to print from the computer to print on envelopes.
  
• Do not use envelopes with embossed or treated surfaces, a double flap, pressure seals, or sticker flaps.
  
• Select either DL Env. or Comm. Env. #10 in the printer driver according to the envelope size you are using. If you do not, the address will be printed in the wrong direction.
  
  

1 : Retract the Paper Support.

2 : Load the envelope against the Cover Guide (the right side of the Paper Support).
Load with the front face UP and the rear flaps DOWN on the left.
A maximum of 10 envelopes can be loaded at once.
*1 Printing orientation
*2 Make sure the flaps are folded.
Important : Make sure that the Cover Guide is set upright.

3 : Pinch the Paper Guide and slide it against the left side of the envelope.

4 : Press the Paper Feed Switch so that the Auto Sheet Feeder lamp lights up.

5 : Set the Paper Thickness Lever to the right.

In the printer driver, select 'Envelope' in Media Type, and then select 'DL Env'. or 'Comm. Env. #10' in Page Size.

(1) Slowly pull the paper out, either from the paper source or from the Paper Output Slot, whichever is easier.


(A) When printing from the Auto Sheet Feeder
(B) When printing from the Front Feeder
If the paper tears and a piece remains inside the machine, open the Scanning Unit (Printer Cover) and remove it.
After removing all paper, close the Scanning Unit (Printer Cover), turn the machine off, and turn it back on.
* Be careful not to touch the components inside the machine.
If you cannot pull the paper out, turn the machine off and turn it back on. The paper will be ejected automatically.
(2) Reload the paper in the machine, and press the OK button on the machine.
If you turned off the machine in step 1, all print jobs in queue are canceled. Reprint if necessary.

1. Do the following
   
   Open the paper support and extend the paper support extension.Open the paper output tray. Set the paper thickness lever to the right side for envelopes.Load envelopes in the auto sheet feeder with the print side facing up. Check the printing direction.Set the envelope in the direction of the arrow.Set the envelopes to the right side of the auto sheet feeder.Pinch and slide the paper guide to the envelope's left side .
   

The error code 5c00 usually means that there is a paper jam or paper path restriction.
If the path is not restricted, the printer will need servicing.
If you want a downloadable user manual for your printer go to
http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&tabact=SupportDetailTabAct&fcategoryid=238&modelid=11995

your printer needs proper cleaning or service

Have you still getting the problem, have you done cleaning of Cartridge, its nozzle and Contact strip.. then cleaning of Printer roller or carriage rack.. Do a Service of it or get it done by Technician.

Also check the feeder tray.. to grab paper one by one by printer.. Manually

Take all updates for printer and OS.

The top-loading sheet feeder accommodates approximately 150 sheets (depending on weight), and the front feeder is good for around 100 sheets. Actual media sizes supported by the main feeder (top-loading) include A4, B5, A5, Letter, Legal, Envelopes (DL size or Commercial 10), 10x15cm(4" x 6"), 10x18cm, 13x18cm, 20x25cm, and Credit Card (54x86mm), while the front feeder is less accommodating with just A4, Letter, and B5.

clean the feeder rupper or replace them

hi i am a Canon certified repair tech for this printer. it seems that your problem is due to a broken sheet feeder unit. what i ahve seem with some new machines is that a plastic shaft that controls ther seperation of the pages breaks. most of these problems occurs with new machine because they are shipped from place to place. if the unit is under a year old it is still under warrenty and can be brought to or shipped to a repair center. even if its not under warrenty any longer you should still call Canon at 1-800-OK-CANON and complain that it has been doing it since you bought it and they will locate the nearest repair center to your location for you. hope this helps.