Garforths' second visit to Tadcsater in pre-season ended in defeat.
A strong Garforth line-up faced a keeper in inspired form, but chances went begging too, and Jay Davis was unlucky with a first half effort that smashed against the crossbar.
The winning goal came in the second half and from Magnets first chance of the game.
It was an unstoppable shot by Ellis Stephenson that flew into the top right corner, beyond Flatters best efforts to reach it.
The Miners now turn their attention the start of the new season, beginning with Saturdays FA Cup game at home to West Auckland.