I just purchased a 1988 45 and we are having head problems. When we pump the head, we get a low flow, but the water is black/brown and brackish. We can flush, and then dry flush, but water seeps back into the head (again, black/brown and brackish). I read the post on the "joker valve". Do you think that this is the problem here? No idea when the last rebuild occurred. Thanks for any advise..One last question. Is it a problem putting a little chlorine into the head... to kill the smell?