Teak replacement
Before I'd replace the teak, I'd try West Marine's Two Step Heavy Duty Teak Cleaner. This stuff is really powerful and worked wonders on my weather beaten teak. $15 would be a pretty cheap solution to the problem if it works for you.Word of caution on application.... make sure the surrounding deck and the hull around the scuppers stays wet. The cleaner can leave a brown stain if the gelcoat surfaces get dry. Other than than, it's easy to use. When it drys, use teak oil or if you like a hard surface, West Marine Woodpro works pretty well.