Where exactly are the heating elements in the PA-28-180's pitot mast? I am flying a PA-28-180 but have been unable to find where inside the pitot mast the heating elements would be.

I would like to know this to verify my assumption it does not work in the airplane I am flying. The Pitot-heat has been on for about 40 minutes while flying through 5C weather, upon landing I checked if it was at least warm and it was not. 

Can anyone verify or reference me some documentation of where and if you would be able to feel the heater?
You don't actually need to get into the mast to know if the pitot heat is working. I fly a PA-28 and during your preflight check if you engage the pitot heat and allow it to run for a minute or two the pitot tube should be warm to the touch. If it is not your pitot heat is not working (or is not reliable enough for flight).