Tapping on the furnace thermocouple makes the pilot light go out?

Question

We have an older Essex SX211 thermocouple and noticed the pilot light was out. I went to relight it and ran the heater, then came back to find it was out again. Re lit it and it goes out when I tap the thermocouple. Could it just be dusty inside or do you think I need a new thermocouple?

I looked online for this part number and the price for a replacement is $168 but the article I read online said it's a "cheap replacement" and ought to cost "$10" for a new one. I did see some Essex ones on eBay for $18. Where do I get the basic replacement?

I'm also confused as whether the thermocouple is this: http://z.about.com/d/homerepair/1/0/u/4/-/-/thermocouple.jpg
Or this: http://z.about.com/d/homerepair/1/0/v/4/-/-/honeywell_standing_pilot.jpg

I think I get now that the "thermocouple" is the long tube with two ends while the "pilot valve" is the large expensive thing.

Answer 1

You should be able to get a generic replacement for that thermocouple for less then $10.00. Anywhere, try Ace hardware.
Make sure you clean everyhting good.

Answer 2

I would check to be sure the thermocouple is not loose from its point of connection. Typically when something changes what it does when being tapped there is a loose connection.

Answer 3

replace the coil with a brass end for 10 bucks . that will usually fix the prob.