Bad luck Tom !!! I went and had a look for these over the weekend, and also had trouble finding them. I first off tried finding them by my usual method of following the OS map and trying to find things from that, but found nothing.
Then I resorted to cheating, and used my my GPS and the 4 fig grid ref I had copied from the RCHM Bodmin Moor Archaeological Survey, but this seemed to take me further away from any likely position, and I again found nothing.
So, I then resorted to my general judgment and stonehunting experience, and found both of the circles without too much trouble, on the saddle between the two hills, right where they should be.
I have to say that the positions marked on the OS 1:25000 map are not too bad (using gps once I had found them) - the trouble is that the trackways across the moor are nowhere near where they are marked on the maps, which leads to failure to find anything else !!!
Something is not right. This message is just to keep things from messing up down the road