Dryer would heat up, then cool off.

After researching the problem, I thought the solution would be to replace the two terminal coil valve, but wasn't 100% sure it wasn't the 3 terminal coil, so I bought both. the dryer is 13 years old so I thought it deserved new coils. My husband was away for the week and I had about 10 loads of laundry to do. I dreaded the thought of going to the laundromat, so I went ahead and ordered the parts, thinking I would call a handyman to install them once they arrived. However, I found a Youtube video showing exactly what I had to do and thought it looked easy enough. I unplugged the machine, removed the front hatch and the 2 small screws holding the coils in place. I unplugged the old coils, used a vacuum to remove the dust in the area and installed the new coils. I popped them back into place, screwed them in, replaced the hatch, plugged the machine in, and VOILA!!!! A dryer that heats!!!!