Here is what I have done for my 10 year old LG dryer that resides outdoors:
- checked the exhaust pipe and there was good air flow with no lint stuck in it.
- checked for continuity between heating element's housing and the wires coming to it - there was no continuity as expected.
- measured temperature at the exhaust pipe when dryer was at high heat setting with no clothes in it. It cycled between 61C(141F) and 71C(160F).
So far I have bought two thermal fuses from Amazon.com and both of them died in few months. Here is also a close up picture of thermistor:
What could be the problem and what additional test to perform?
Update #1: Picture of back draft flap. Seems clean to me.