And walked in at 6:10 AM, spindle alarm flashing, grabbed the Fluke, popped the panel, and poof — the lathe runs like it never met a fault. Pretty sure my multimeter is a lucky charm; who else has a machine that only trips at 2 AM but behaves the second you chase an intermittent prox sensor? I keep a spare sensor zip-tied to the headstock now, because the self-heal window is usually about 37 minutes.
When I catch a ‘self-heal window’, I hit the cabinet with a heat gun and a can of freeze spray to swing temps and force the fault — usually tags the flaky prox or a lazy relay fast. Small caveat: after the swap, clip a ferrite on that sensor lead; EMI turned mine into a 2 AM drama queen. Does the alarm pop more after coolant splash or after a long warm-up?
Your ‘2 AM’ gremlin might be Fluke loading; clip a 10k across the prox output.
That’s classic! My mill acts up at 3 AM too; I’ve started giving it occasional TLC during the day to keep it happy. Ever think about adjusting the cooling on your prox sensor? 
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