HP smart tank, intermittent paper jams

[Less5]

I have a new HP smart tank 7302 printer.  It has a persistent problem paper jamming.  After clearing jam it usually will print 1-3 pages with crease near top of page and then jam again.  The error message reads E3 or E4.  The problem appears to be the rollers? Any ideas?

[r01]

I have a HP smart tank 7301 that's about 3 years old. It has started developing multi-sheet paper jams. These are generally caused by the paper separator rollers. (We don't like this printer as it continually goes off-line. We have to unplug the power to fix it.)

HP has all the roller hidden. DO NOT turn your printer on its side or upside down as ink will spill causing print head failure. If this happens, remove each print head and clean the ink off the contacts and elsewhere. My black ink head was just shorted by the wet ink. Cleaning them fixed it.)

About the jams, I cleaned the few rollers that are accessible.  I pulled out the paper tray (lift the front and rock side to side). Above the tray is a gray platform for the printed pages. Pull it forward and it will come out. Inside the hole for the paper tray is a black plastic assembly with 2 rollers near the center. On the left is a black lever that releases the roller assembly so it hangs down. I cleaned its 2 rollers and a row of 5 small rollers in front of them with a rag and denatured alcohol. These were all I could access. I doubt it did anything but hopefully it did.