The thermal protector/starter for this single under the counter lamp failed.  Is there a replacement for this part?

Does your fixture contain a simple choke reactor type ballast with starter?  I'm guessing you have a fixture that looks something like this.  On the inside, it probably looks like this.  Is that correct?  So it's not working and I assume you've eliminated the bulb as the reason why.  Does the lamp light up at all?  Does it glow only at the ends?  Was it slow to start before it stopped working altogether?  If it was taking a long time to start or is stuck in preheat mode, the starter is probably bad starter.  Your starter is the cylindrical metal or plastic can.  You'll want an FS-2 and they can be purchased from just about any hardware store.  An FS-22 will also work.  If you don't see a starter, then you either have a starterless ballast (magnetic rapid start or electronic) or you have a hardwired starter glowbottle.  If you have a small coil-type ballast similar to the picture, then there must be some type of starter.  If it is hardwired, you can still repair it, but it's a little more difficult.  My recommendation would be to remove the glowbottle and put in a starter socket wiht replaceable starter.  Starter sockets are not as readily available as the starters themselves, but can be purchased online.

Does your fixture contain a simple choke reactor type ballast with starter?  I'm guessing you have a fixture that looks something like this.  On the inside, it probably looks like this.  Is that correct?  So it's not working and I assume you've eliminated the bulb as the reason why.  Does the lamp light up at all?  Does it glow only at the ends?  Was it slow to start before it stopped working altogether?  If it was taking a long time to start or is stuck in preheat mode, the starter is probably bad starter.  Your starter is the cylindrical metal or plastic can.  You'll want an FS-2 and they can be purchased from just about any hardware store.  An FS-22 will also work.  If you don't see a starter, then you either have a starterless ballast (magnetic rapid start or electronic) or you have a hardwired starter glowbottle.  If you have a small coil-type ballast similar to the picture, then there must be some type of starter.  If it is hardwired, you can still repair it, but it's a little more difficult.  My recommendation would be to remove the glowbottle and put in a starter socket wiht replaceable starter.  Starter sockets are not as readily available as the starters themselves, but can be purchased online.

Thanks for the quick reply.  The Lamp does not light up or glow on the ends, think I must have what you refer to as glowbottle.  The lamp is new .  I checked the Ballast with an ohm meter and got the same reading as a new one. What I see is a hard wired small glass device much like a mini Christmas light that appears to be burned black.  There is also a small (in physical size) capicator wired in parallel to the glass device.  So rather than replacing these parts are you suggesting I modify the lamp by adding an F2 or F22 starter?  Will these starters provide the thermal protection?  I have access to an old lamp with a starter that I may be able to cannibalize.

What I see is a hard wired small glass device much like a mini Christmas light that appears to be burned black.

Exactly this is the starter - what is reffered as "glowbottle" (as it is the way, how it work internally - glow discharge is used to sense the lamp voltage and heat up a bi-metallic switch. All this enclosed in the glass vessel, so the "bottle".
The fact, it is black, does not have to mean anything by itself, it may indicate it have been in use.
You will find essentially the same device in practically all two pin starter cans.

There is also a small (in physical size) capicator wired in parallel to the glass device.

This is used to help the switch in the starter to switch OFF (quench the arc), so the energy stored in the ballast become all available for striking the lamp. But frequently this ii a source of starter failures: It break down and so create the "stuck starter" fault (lamp ends glow and nothing else happen)
Mostly the starters work even without the capacitor, maybe their lifetime could be shorter.

So rather than replacing these parts are you suggesting I modify the lamp by adding an F2 or F22 starter?  Will these starters provide the thermal protection?  I have access to an old lamp with a starter that I may be able to cannibalize.

Replace the existing starter (the "Christmas lamp") by the FS2.

But first of all, check, if the rest is working in order. Because most frequent starter failures are the starters getting stuck, so they only keep the main tube end's glowing and nothing else happen.
But your description correspond to some open circuit problem, so I would rather suspect some wrong contact somewhere. But it could be the starter as well, so (next will mean working on a live circuit, so proceedd only if you are familiar with working on a live electrical circuit and be careful):
Keep the fixture open, install the lamp, plug it into the mains and turn it ON
Take a V-meter and measure the voltage across the starter. There should be the mains voltage. If there is no voltage, there is clearly some bad connection to look for.
Take a wire (insulated, except from the ends) and try to short out the leads on existing starter. The lamp ends have to warm up.
After disconnecting the lamp have to light, or at least flash (or at least after few trials). When it lights, it is the starter, what is wrong. When it does not, look for some other fault in the circuit (it could be broken lamp filament, some contact resistance somewhere,...)

quote author=afang link=topic=3156.msg20392#msg20392 date=1377916496]

What I see is a hard wired small glass device much like a mini Christmas light that appears to be burned black.

But first of all, check, if the rest is working in order. Because most frequent starter failures are the starters getting stuck, so they only keep the main tube end's glowing and nothing else happen.
But your description correspond to some open circuit problem, so I would rather suspect some wrong contact somewhere. But it could be the starter as well, so (next will mean working on a live circuit, so proceedd only if you are familiar with working on a live electrical circuit and be careful):
Keep the fixture open, install the lamp, plug it into the mains and turn it ON
Take a V-meter and measure the voltage across the starter. There should be the mains voltage. If there is no voltage, there is clearly some bad connection to look for.
Take a wire (insulated, except from the ends) and try to short out the leads on existing starter. The lamp ends have to warm up.
After disconnecting the lamp have to light, or at least flash (or at least after few trials). When it lights, it is the starter, what is wrong. When it does not, look for some other fault in the circuit (it could be broken lamp filament, some contact resistance somewhere,...)

Well, much to my surprise the lamp came on. I have switched it of & on several times and I am leaving it on now to see if something could be overheating.  I am suspecting a loose connection.  Thanks for everyones help.