Quote Originally Posted by fred_dot_u View Post
I'm not sure which is which in the photos, but if the limit switches/sensors are in the upper right of the second photo, it gives me a clean view of the connections. You have a couple useful tasks ahead.

Identify the working sensor wiring and swap it for the non-working connection. For this, you're really only looking for the steady LED at this point, as you don't want movement or want to keep things to a minimum. Swapping at the board will give you a better reference. If suddenly the good one goes bad, it's on the board, which is the more likely circumstance. That will be confirmed if the bad one goes good, obviously.

Examine the connectors as you remove them, perhaps tugging on the individual wires that enter each connector. If any single wire moves freely and/or comes out of the connector, that's a good/bad sign. Good that you found it and will fix it.

With everything connected in the usual manner, push on the socket for the bad sensor connection. If there's a cold solder joint on the board inside the socket, this may create the intermittent connection. It's an easy fix if you have a cold solder joint, but the labor in disconnecting everything isn't all that much fun.

You suggest that wires can have internal breaks, but it's been years since I've come across such a failure. Your printer would have to have been misused and many years older for that to be high on the list. I won't reject it outright, but it's less likely than a cold solder joint or a loose prong inside the connector.

Do you have a digital multimeter and/or a soldering iron? Either are pretty inexpensive if you buy cheap, but if you plan to be a 3D printer mechanic (plan for it), you'll want a decent DMM and a soldering iron with a couple different size tips in the 25-40 Watt range.
Thanks Fred!

I have both but hopefully in this case I won't need them.

The X1 sensor socket clearly is the culprit. It makes a loose and sloppy connection and one of the JST wire connections even came out with little provocation. I opted to try a very conservative fix of using 3 plastic shims to immobilize the JST connections within the plastic connector housings which has removed all of the apparent wiggliness from the socket. I'm looking for any opportunities to further insulate the internal connections from any external pulls on the cable bundles and then I'm going to close her up and see if i get all of the optical sensors to light up in the face of a bit of simulated jostling. If they pass that, I'll be overjoyed and proceed to trying to home the device, level the device, and await the arrival of the replacement extruder.