Are you leaving it switched on? I use Epson printers... always have, and I've found that if left on, they block a great deal. Switch them off as soon as you're finished, and leave them off until needed again, and they hardly do this.
Another thing I've noticed... call me cynical if you will, but the cheaper Epson printers seem to use more ink.. Hmmm... and it's more expensive. Makes you wonder. I reckon Epson don't make much, or any profit on the low end printers, and make their money on inks. Like Razors... you can buy a new razor for a few quid, but when you need new blades, they're sometimes £10 a pack for certain razors.
The 830 is still a great printer however. It has a lot in common with the old 810, which I still use. That does the same thing. Leave it switched on, and it will clean it's heads all the time... every time you use it in fact. Keep it switched off, and it's much better.