McMahon scored from a free-kick and his corners led to Trinity's other goals
Gainsborough Trinity earned a second away win in five days, beating Solihull Moors 3-2 in Blue Square North.
Trinity led 2-0 after 20 minutes thanks to Matt Austin and Lewis McMahon, but the hosts pulled one back from a corner after Adam Sollitt had saved a penalty.
In the second half James Lukic bundled home to restore the advantage before Solihull scored with 11 minutes to go.
Manager Steve Charles told BBC Radio Lincolnshire: "I'm pleased, but they do say a win hides a multitude of sins."
Despite taking maximum points on their travels so far this season, Charles felt there was still work to be done.
"In the last two games, when we've gone in front we've panicked a little bit towards the end," he added.
"I don't know if the lads are trying to send me prematurely grey but I'd prefer it if we kept the ball a bit better when we're ahead."
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