I ran into a few problems finding this place, so here's what I learned. The Forest Road designations are obsolete, replaced with (impossible to remember) 4 digit descriptions. 11 miles from I-17 turn right at the roadside "kiosk" for the National Monument. Continue on that dirt road (high clearance recommended) for about a mile through the corral and two cattle grates, and then continue another ca. 0.4 mi until there is a road to the right. It's another 2mi to the windmill. It is recommended to park at the windmill and walk (though the road continues further). Walking from the windmill, I headed along the continuing road for a few hundred yards before angling right to crest the ridge/mesa top. Once I c rested and could see ahead, I took a WSW bearing which pointed me toward the distant Bradshaw Range Hill with the Rhyolite band near the top. Walking that direction across the open mesa, eventually I saw paired High Voltage towers in the distance. It turns out the ones on a line with the banded hill are NOT the right ones...you want the pair to the right, the last pair before the gorge (though you don't know that til you get closer). I didn't see any numbers on the towers.
In reality I didn't find the right road to the windmill but instead took a different road which went right just after the corral but before the cattle grates. This is not a good road and I ended up parking a mile short of the windmill. My posted distance reflects the longer approach and some wandering around the ruins. The GPS route I post reflects my windmill to ruin route...if you bear toward the correct towers you can get there more directly.
The other triplogs are correct in that the ruin walls are crumbled and overgrown with vegetation and the petroglyphs are the highlight. I ran into a couple there who were quite knowledgeable about the ruin and glyphs having been there several times before (BTW they got there via ATV). They were curious about how I got the information to find the place and were initially guarded, but they did give me a few tips on where to look for petroglyphs.
I'm sure I only saw a small fraction (just judging by photos posted on HAZ) but what I saw was impressive. I made a half-hearted effort to find the supernova glyph but I had little time and had to get back.