Mike,
Did you torque any screws on the board containing the Rx/Tx relay, or any metal shield covering portions of the circuitry?
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Sometimes these kinds of issues are caused by hairline fractures on a ckt board, and mechanically or thermally connections become intermittent. Mechanical Flakey.
Sometimes these kinds of issues are caused by cold solder joints, also impacted my mechanical or thermal stress. (Thermal Flakey).
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Now, it could be the Rx/Tx has pitted contacts such that the Common (c) center connection (Armature) does not shuttle between Normally Open (nc), and Normally Closed (nc) positions.
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Did you at least verify the Rx/Tx relay was firmly seated?
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Glad you got it working. Maybe it just wanted you to admire it from the inside.
Sam
