HP Laserjet 1012 keeps feeding paper after printing one page and jams

[pmg956]

Printer is not connected to a computer. Trying to get the self-test feature to work before connecting. 

Power off

Power on

Printer goes through boot cycle and stops normally, with green Indicator light.

Press the button to self test (green or orange-pink button)

Prints a test print page, and then keeps cycling over and over, pulling another sheet into printer and jamming.

I have replaced the paper seperator device in the back. No change.

[Valsimot]

On the side you have a paper pickup solenoid it gets sticky with time, use duck tape to fix the sticky part and the printer will feed paper normally.

https://www.youtube.com/watch?v=-5oqvlkZRSo  not your printer model but the closest I could find, the sticky solenoid is visible @1:10 of video