Check the fuser. If it is the fuser, you should be seeing 3 dark lines on the fuser film. Here is the picture about how the film looks like:
Changing the film usually solve the problem. However changing the film itself is difficult. You have to remove and basically disasseble the fuser, and change the film. However it is fairly cheap and if you decide you would like to save some money, here is the link available in ebay:
Or, simply search for 'P3005 Fuser Film' and you will find a lot.
Other than that, you can change the entire fuser. Please note that fuser for P3005 is not consumer installable part. You still have to take out some parts in order to change the fuser.
The parts are available from many parts supplier. Simply google 'P3005 fuser'. Usually around $100 for a refurbished fuser.
You can also recycle your old fuser and get some moeny! (about $15-$25 per fuser).