Have you been visiting it long? Its been about 8 years since I was up there but it was pretty hard to see even back then...

I second the speaking to EH. Might as well involve them from the start as they would have to give permission for any works to take place. Who manages that moorland, there may already be a plan in place.

That's the horrible thing about these places, they're so old and special yet hardly anyone cares less, the places there are a hard one to see but sometimes that's the thing that's help protect them over all these years [The fact not many people know they're there], but once your eyes in you can see them better, I'd say try talking to someone official but in my experience they don't care less either, I'd say you sound like it's protector to me, these places do need looking after and we are all the guardians of them, sorry i can't be of any practical help, It's good to know the place has you to care about it though.