I've repaired quite a few 4800/4880 in the last couple of years. Only do a couple of head cleanings at a time, otherwise, if you are using clear cleaning solution, I've found it gets into the multi-sensor. Error 100030. (Remove the print carriage, remove sensor, clean/blow out, reinstall.)
Also, check the capping station. The rubber edges tend to wear down and then create problems when trying to 'suck' the ink into the capping station. This can be frustrating, thinking its a clog in the head, but not. You can replace just the cap (lots of work), but you'll still have to take the entire capping station out. At that point, do the whole thing for about $150.
If you have any problems with the 4800, let me know and I'll try and walk you through.
Oh - found this the hard way - never replace the printhead with the power cord still plugged into. You'll pop the F6 fuse and have to hard wire one onto the main board.
