Just purchased a 10 year old house and noticed an orange stain between the panes on a double pane vinyl window. It appears there was an "egg" stain on the exterior of the window that may have breached the seal and there is orange bacteria(?) between the panes? The window has brass bars between the panes and would guess that it is quite expensive and would be difficult to match/replace. Any ideas on how this stain can be cleaned?