Redfield scope problem.
I have a 1 3/4x - 5x variable Redfield scope which I bought new back in 1978. I haven't used the scope during the last ten years. The last year that I used it, the image through the scope had gotten dim and the image wasn't sharp. The problem hasn't gotten any worse over the last decade, of course, it hasn't improved either. Is there any fix for this problem or is it time for a new scope?