Uneven wear on valve adjustment screws, what might cause this? Options

[75914-L20C]

'75 1.8 liter, 170XXX miles on completely stock engine, heads never been off, case never opened.

I was adjusting the valves last night and took out all the adjusters to check for pitting, and noticed the off-center wear pattern and some pitting at the outer edges of the adjusters.

The adjuster at the top of the pic looks like I would expect with criss-crossing wear patterns all centered on the adjuster face. The adjusters in the bottom row are the worst ones with a much wider wear pattern offset to one edge. I didn't think to keep track of which cylinder or intake/exhaust they came from until they were already in a pile on the floor.

I checked the clearances before removing the adjusters and all were in the 0.006 to 0.008 range. I think the 0.008s were as a result of setting those a little too loose last time.

Is this a sign of mis-adjustment or some type valvetrain wear?



Thanks,
Pete Klager