I have just bought a lexmark p707 i have installed it okay as far as i know. The problem is that the fonts come out half black and half pink and green and with lines going thru them pictures print okay though!
I have never used a P707 but have a Lexmark X75. From what you say, you must be using your colour cartridge to print black text which can be wasteful. Therefore, assuming that your black cartridge is OK,I suggest you go in to Wordpad and make a document having a row of RED capital Rs, a row of BLUE capital Bs and a row of YELLOW capital Ys and choose a large font size, say size 20 or 24. Print this document out and you should be able to tell which print nozzle or nozzles are blocked. If any are blocked, remove the colour cartridge and stand the nozzle end in about 1/4" of hot water (not boiling) in a saucer for 10 minutes taking care not to touch the electrical contacts. Then stand the cartridge on a damp paper tissue until all the colours are flowing OK. You may have to repeat the hot water once or twice to get them flowing freely. When they are flowing OK replace the cartridge and run the clean and re-alignment programs. I hope this helps.
What cartriges have you in the printer? I have the 706 and it came with colour & photo carts, in the maintainance section of the lexmark solution center are the carts selected properly ie.left colour, right photo or black. the manual with trouble shooting is on the istallation disc if you need it.
Not having a 706, I can't really help any further with your problem but I would suggest that you get a BLACK only cartridge as it is wasteful and expensive to use a colour cartridge just to print black as it uses all the colours and, therefore, three times the amount of ink necessary. It might also cure your problem.