Thank you SO much for taking time to post this. My 2006 water heater is 8 months out of warranty and the thermocouple failed. I called Whirlpool and they said it would be something like $35 + shipping for a right-hand adapter.. Talk about extortion!

So I bought the $8 universal right-hand thermocouple from Lowe's. Then I went to Harbor Freight for a rotary tool (like a Dremel) and grinding attachment for a whopping $17. Spent over an hour grinding the slot, but it worked flawlessly! I'm sure an actual Dremel would get the job done much faster, but at Lowe's the cheapest one was around $50, and I wanted to stay under the price for the Whirlpool adapter.

The symptoms for me was that the pilot would go out randomly. Sometimes it would remain lit for days, and sometimes it would extinguish within an hour.. But relighting it would take 20 - 30 seconds max before the pilot button could be released. I even tested with a voltmeter and had a reading of 26.5 mv. But apparently the voltage would occasionally drop and the safety switch would release.

Again, thanks for the post. No more cold showers You made my day!