New spa problems

I have an old spa.
At some point recently it stopped heating water. It still circulates, though.
I have traced the problem to a faulty thermostat switch (with a knob to set desired temperature).
The proof of this is that if I electrically connect two terminals of the switch, then the heater relay closes. That is not happening if the thermostat is set even to its highest setting.
Here's the weird part. Three years ago I had the same problem -- when I moved into this house, the spa was not working. So I went to a local dealer and bought a new thermostat and installed it. It lasted about that long, and now it i s bad again. WTF? Any idea just what might be possibly wrong, or are these thermostat switches really that bad?
thanks
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes. That type usually has "points" like an older car distributor. Shut the power off and slide some very fine (400/600) sandpaper between the points and pull it back & forth. Make sure you get BOTH sides.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

A-ha!
I think that that's it!
An additional tidbit is that as I rotate the knob of the thermostat, I do hear a "click". At approximately the point that I would expect. So the thermostat "clicks", but somehow does not close the contacts.
So, your suggestion is right on the mark, but I want to hear a little clarification. Do I need to take the t hermostat body apart?
thank you!
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They click shut but since the points are burned, the current has a hard time passing thru.

I didnt, I just shut off the current, took one (front) side off the control box wherein the thermostat is found, wound the thermostat switch to its lowest setting (opens the point gap more) and put the sandpaper or a "points file" in there and smoothed them down. I also found a small hole in the thermostat housing that allows an 'allen key" to be inserted..when it is turned, you can see it changing the gap- it allowed me to put the desired setting into the dial..I put the dial about halfway, then turned the allenkey til the points clicked.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Rudy, thanks, I am away from home, but I will do exactly as you suggest when I come back. thanks.
igor

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.