HP B209 cannot do paper feed only on print command from a PC. it works fine with copying function.

I would start with putting in a new ADF kit.

https://www.printersupplies.com/p-ljm2727adfpjk.html

Problem:
The 'drop down paper grabber' gears are not turning, and the printer gives you an error saying to make sure there is paper in the printer.
All of the fixes on the internet are for working printers, and their approach is to clean the rollers if they are not grabbing the paper. They are assuming they are turning properly and the rubber grabbing wheels are wither dirty of dried out.
In my case, however, the gears were not turning, and so the rubber grabbers wheels were not turning, even though the whole 'paper grabber' unit was dropping down properly
Solution:
Just inside the paper loader tray, along the top, there is a metal rod. It is about 1 inch from the front.
The gears from the drop down paper grabber are supposed to meet a gear that resides on this rod and sort of floats on it. However, the gear on my printer slipped to the left, and was not making contact with the other gears.
You can gently put your finger on the gears as you do a copy command, and confirm this.
To fix the printer, I just slid the floating gear over to the right and into place, and the paper began feeding properly.
Why there is nothing to keep the gear in place is a mystery to me.

Clean the feed rollers.

The paper feed roller(s) are probably dirty.If you can reach the the roller that pulls in the paper try to clean it with alcohol or kitchen type cleaner if you do not have alcohol make shure it is fully dry before trying to print.You can also wet one sheet of paper with alcohol where the roller will grab it and tell it to print while firmly holding back the paper as you do not want wet paper to feed into machine repeat if needed

if the paper fed rollers do not drop onto the paper it is possible the cam is jammed.
turn the unit off remove the paper and try to pull the paper fed arm downwards and try turning the rollers counter clockwise also.
if the arm drops power back up and retry a pcl command if not you may need a technician to strip the unit and adjust the cam gearing or solenoid action depending on the feed and separation capabilities

hi that is a paper jam..this happens coz the rollers in the paper feed tray are not functioning well...try cleaning the paper rollers..

Paper feed problems are very common with HP officejet printers but don't panic...

Few things to try..
1. Check that when the printer tries to feed paper the wheel is dropping down and making contact with the paper.

2. Make sure you have not set the paper guides so the paper is too tightly held... try loosening them

3. Watch this little video on how to fan-apart paper and try doing this to get some air in between the paper sheets.. This often resolves many of the problems.

4. Try changing the paper for something a bit coarser or even cheaper as HP printers can be a bit "Fussy" about the paper they will feed best...

Hope that helps...

Remove the paper cassette and the toner. Turn the printer upside down and look at the feed roller.

It should NOT spin freely, drive tabs may be broken off of the roller shaft.

Verify your paper settings match between the printer and PC. If a roller is dirty the paper might feed late.

there is nothing wrong with the roller becoz it is picking up the single seet what you can do is you put bunch of paper while you placing the paper sheet dont put deep inside just insert like when feel resist leave it. give the print command it will automatcally pick up sheet one by one. bye