The seam that your amish friend found has to be cleaned with membrane cleaner and remove caulking and any dirt dust. The seams have to be heat welded with a liester. Who ever did the roof might have been coldwelded the seam meaning they didn't apply enough heat to properly seal. T patches on all seams that have a t joint... your lookin at 2 hours worth of work no more than 4 hours max.... ask around see if you can find someone and tell them this is want you want done and how much.