The splines on the starter are constantly in contact with another idle type gear that is in constant contact with the starter clutch. They never disengage each other and the only gear that's chewed up is the starter splines. All of the gears spin in one direction freely, so the clutch seems to be working fine. That's why this is so baffling to me. Now that I'm not worried about getting the balancers out of time by spinning the starter clutch in the direction it moves freely, I think I'll turn the starter clutch around a few times and feel for dead spots or resistance. Also, the position of the starter itself is not adjustable, but there is some noticeable damage to the bottom of the engine, like the previous owner drove through a big pothole or over a curb and bottomed out the engine case bad enough to take a small chunk out, so I'm wondering if the position of the starter also took a hit and got bent out of wack to a position where it wasn't fully engaging, and over time got damaged to the point it won't engage at all. Just brainstorming, thanks for the replies. I'll update after we work on it some more, but it might be a few days.