Use the correct type of soldering iron and flux. Strange question for a sporting good store. Back in the day, before cell phones, you could be sure any employee at Radio Shack could inform you on the proper tools and techniques but today, you yourself could be a Radio Shack employee. Watch YouTube videos, visit Instructables or better yet borrow and read a book from a public library.
Make sure the points on the circuits are clean real clean so its bright and shinny
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