HELP!-HP 1012 Laser won't print after I cleaned Pick up roller & adjusted spring of Separation Pad

The original problem: HP LaserJet 1012 was feeding xtra sheets which jammed.

I cleaned the Pick up roller & cleaned the Separation Pad
& I carefully the stretched spring of the Separation Pad: this solved the feeding xtra sheets problem for awhile.

I also put the toner cartridge in wrong, at one point,; with right & left sides reversed
& it jammed on the left side & was tricky to pull out.

Now the HP LaserJet 1012 won't print when I use the Print test...

HELP!-HP 1012 Laser won't print after I cleaned Pick up roller & adjusted spring of Separation Pad