It is not necessarily the number of prints but the age which can effect the fuser teflon sleeve. Your sleeve has started to tear and is not covering the side of the fuser which is the fault you are getting. Your printer is the same as the P3005 but has the scanner on top. The link below is for a kit you can purchase to replace the fuser teflon sleeve by yourself. The kit comes with instructions for removing the fuser from the P3005, but basically it is exactly the same as you just disregard the scanner above.
http://www.fixyourownprinter.com/kits/hp/K100
http://www.fixyourownprinter.com/kits/hp/K100