After checking the fuses and thermostats with a multimeter, I discovered that my heater element is defective. Should I replace anything else with the heater element even though they are not defective:confused: 
You should only need to replace the heating element if the other devices in the heater circuit check out OK.
I would check the rear support rollers, the front support glides, the belt, the idler wheel, the drum seals etc.
You may as well give it an overhaul when you have it apart.
Also clean the interior including the blower wheel.
It is also a good time to check/clean your vent system.