Solenoid failure mystery

[JackofallTrades]

I didn't see where else to post this so feel free to move it to the proper section if there is one.

I have a pull type solenoid very similar to what is shown here.

**broken link removed**

Yesterday, it stopped actuating. After testing the drive circuit, I checked the solenoid itself.

Originally, this solenoid had a coil resistance of 4 ohms.

Now, not working, it has a coil resistance of 10 ohms. I'd like a theory on how this came to be.

If the wire had burnt through, I would expect an open circuit. If the insulation had failed/melted and coil winding where touching, I would expect a lower resistance. The only theory I have is that this solenoid must use multiple windings in parallel. One or more of these burnt through, leaving only less parallel coils and thus a higher resistance?

Thoughts?

(The windings are sealed in a metal case and I cannot easily inspect them.)

 

[betwixt]

I've never come across one that increased it's coil resistance although it is possible, but unlikely, the copper has changed properties. The most likely scenario is there were two coils in parallel and one has gone open circuit.

Brian.

 

[ahsan_i_h]

Momentary (one second) apply double voltage. If solenoid works, then there may be two coils in parallel.