I emailed NorthBay and they replied very quickly with a package deal. I ordered 5 bottles of refill and two gears for $30. The order arrived within a few days. I refilled the first printer according to the instructions and it worked perfectly.
Toward the end of May, I refilled the second printer. This time the print-outs were light, but not as light as the printer I threw away. They were usable, just not perfect. So I set the printer to its darkest setting and printed things in bold. It was a minor annoyance but it worked. In June I decided to call Northbay to see if they had a solution. The phone was answered promptly. The person was courteous and friendly. He explained that there were other factors involved, such as how much exposure the particular drum had undergone and once in a rare while the toner wouldn't work as well. He looked up my order and said he was sending me three bottles of toner specially formulated for just such situations, which is darker than normal.
This is customer service at its best - the kind I like to give my customers. The order was long completed. Feedback had been posted. If he had explained that sometimes a particular drum was too deteriorated to work perfectly, I would have accepted that. But he went above and beyond. I wasn't aware that other companies existed which also give the same service I strive to provide. So I recommend that you contact NorthBay Toner if you need laser toner. They have cartridges compatible with HP12A which contain 50% more toner.
NorthBay Toner on ebay or call (877) 597-0737