HP L7680 and the yellow ink problem

So my boss has this printer and I've been workin on it to try and get it to print. Here's the deal:
-It keeps saying the yellow ink cartridge is empty (understandable)
-we replaced it with a brand new one from Staples (88 Yellow cartridge)
-Put the new one in and it still has the problem...Saying I'm out of yellow ink
-There are obvious splotches pointing to the ink leaking and spraying around parts on the inside, I cant get in and inspect because HP has screws that make it harder to get in (thanks)

now... I've read multiple forum posts at HP about the same exact problem with Yellow (no other color). But no one has yet responded to them that I've seen. One is [url=HP Forum][/url].

Other issues: LCD display on it freezes on "Adjusting Printer" and when I try to shut down at any time it will stay on "Shutting Down." I've let it "shut down for more than 24 hours and it wont move.

Sorry for the long post. ANY help would be appreciated as my checks are printed here... thanks in advance!