TONY McMillan's penalty save was the turning point as Runcorn kept moving in the right direction towards Conference North.
The Linnets won convincingly at home for the second time in four days, but McMillan was the hero for stopping James Turley's 42nd-minute spot-kick.
Turley had been decked by Peter Ellis but, just when it seemed the home side had thrown away an early two-goal lead, McMillan got down low to his right.
Two goals in the first nine minutes from corners gave Runcorn the best of starts.
Matty McGinn headed a half-clearance into the mix from the edge of the box, for Carl Rendell to lay the ball off to defender Spearritt.
Rendell nodded in the second from point-blank range when Anton Lally headed back McGinn's right-wing flagkick.
But when David Ness deflected the ball into his own net trying to deal with a 23rd-minute Colin Hunter shot, the unease increased.
The second half was largely bereft of chances until the 74th minute.
McGinn made ground and Ged Courtney's run down the inside-left channel provided options, before his pass across the six-yard box saw Rendell steer home.
Matthew Platt wrapped things up with an exquisite chip late on after his initial effort was saved.
RUNCORN: McMillan, Spear-ritt, McGinn, Nolan, Ellis (Courtney 64), Ness, Lally, Morley, Lightfoot (Platt 83), Rendell, Garrity. Sub: Aldridge. Att: 188.