The error code 1686 means black ink level gone, press and hold the "stop" button for 10 seconds, so does with color side.

Usually, the printers with cartridge number 61/60 can work on single cartridge mode, e.g. deskjet 3050A all in one machine.

by using some compatible hp 950/951 cartridges, the printer will pop up ink system error massage and stop there; what we've done was just refill the original ones and install them, problem solved.

by pressing and hold 2 buttons on D7260, we fixed the error 18a0001

(Bottom Left)  (Top Left)  (Bottom Left)  (Bottom Left)  

1) Enter Service mode by pressing: menu-copy-#
2) select: Test Mode
3) select [8] printer test in test mode
4) select 3 [eeprom clear]
5) select 0 [ink count]
6) press the [stop/reset] key (returning to the state of 3), and press the [on/off] key

Press and HOLD all following buttons: Power, Load/Eject, Stop, B&W, Color. RELEASE BUTTONS
After this printer turns on, you'll see "Init eeprom" on printer screen. Press Color button to clear protection counter