It's definitely a sensor of some kind, as it just connected via bog standard T-piece.
It could be the pump is designed to only run for a set period, after a set pressure has been reached, then switch off. If it's a continual pressure pump, then I suspect it's not meant to run continuously on such a small machine.
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I'd guess just a pretty standard insert parting tool would work (small tip type, not big flat blade type), with the holder cut shorter if needed.