Trying to Troubleshoot Problematic Door Sensors

I have a couple of webcore pistons that interact with my Front Door and my Back Door (on is relocking my smart lock and the other is for doing some nice things with security like interacting with Tasker to play audio on my panels during Entry and Exit. 

The problem is, for some time I thought the pistons were buggy, but now I realize it's either the sensors or something on the Konnected side. My doors have sensors that are about 5-7 years old and use plungers drilled into the door frames. 

Support is suggesting there may be resistors in each line, but this install had a LOT of them at the vista panel in the master bedroom so I don't see why they'd put most resistors at the panel and then a couple inside the door frames. I'll be taking those out in the coming days to be sure as I just ordered what I hope are drop-in replacements. 

I want to be sure that such sensor don't have any sort of resistor built into them by default. Do sensors come that way for some uses? 

Back to the issue: 

The pistons are failing because the logs show them reporting all sorts of erroneous reporting on the status of the door. For example, I can enter the house and ST will show the door cycling between open closed three or four times when it only was open and closed one time. 

To prove it wasn't the piston I added a wireless multipurpose sensor to the door and recoded to point to it and it reports everything perfectly accurately.

Support mentioned it could be a bad module, but that seems unlikely. Why? I have an 18 zone (3 module system) and my two doors are on two different modules and both have the same issue. What are the odds that two of my modules are bad in the same way?

Can anyone help point me in the right direction or tell me I'm already heading that way with what I'm doing? I suspect if any sensor is likely to fail early a door sensor fits the bill as it gets a lot of daily use. 

I did find out that there is no resistor on the wire to the konnected panel. Had to unscrew the plunger, remove the door trim and then search behind the panel to track the wiring, but that's now done and there definitely isn't one. 

So that leave a faulty switch or konnected. The new switch will be here in a day or two.

If you have the wires exposed on the door side - twist them together. Connect the other end to the Konnected board. It should show as closed. Take the wire apart. It should show as open. If that's the case then it's the sensors. 

FYI, it appears the main culprit was a worn-out sensor. I just replaced it and it now fires off reliably. It was only five year old so I'll need to keep an eye on the new one.