^^^^ +1; yes, rust/debris/whatever in the channel is an issue. But any _REPUTABLE_ glass shop should clean that up for you as part of the job. If it needs actual paint, they should give you the opportunity to do it. We've had two windshields done by Safelite. Here in Madison, Safelite bought up a local "chain" called Auto Glass Specialists. They came out to the house, cleaned up everything, then gave my wife a few minutes to paint what needed painted, then finished the job. Been flawless ever since, through about eight Wisconsin winters/springs/summers/falls.