So I started this house a couple of months ago (windows and conny about 8 months old) I text her to ask about payment for last clean as she paid me online first time. She says can u come back and redo them black marks on PVC :huh: I go have a look today and sure enough every bottom rail has black run marks down them. Not just at run off points but all along rail. So I'm like eh :angry: Just a rub of restorer and they came up like new. I'm assuming its rubber seals but new windows and don't wanna be cleaning bottom rails after every clean. Ideas lads?