It is located on top of the heater element assembly, and is probably due to an overheat situation.

You'll need to raise the top of the unit to get access to it.

*** turn off power to the dryer, or unplug the power cord ***
Approximately 1 inch, in from the corners, you'll need a putty knife or thin flat piece of metal(butter knife is good also), insert the knife into the seam between the front panel and top, you'll feel or see the spring clip(s) that hold the top down to the front panel, press in on the clip, and lift up on the top.

Once you've got the top up, in the rear left corner of the cabinet, you'll see the heater assembly and the fuse, thermostat.

Follow the instructions that come with the fuse kit, and replace both parts.

Reverse procedure, and test run the unit,

Check and clean the exhaust pipe and venting tube as best, and as far as possible.

Good Luck,
:) :) :)