My folks lead valley started leaking a few years ago, they never thought about a proper replacement repair job beyond slapping some lead sealant over the cracks every few years. This year they've been trying since June to find a roofer to properly replace but have been let down. My dad bought some Bostik Flashband as a temporary repair for winter but when I went to roll it down the valley, it stuck all the way til it hit the lead sealant patches then wouldn't stick. I see products like Lead Mate are silicone based and I believe bitumen based products don't adhere to it. Any advice on getting this to stick? Cleaning it is a pita but Scewfix support said even using a primer won't work. I'm guessing slapping some Black Jack over it won't work either. Any suggestions on cleaning up the lead beyond a wire brush?