Insane Hydraulics
Bold and audacious blog about fluid power
This is a servo-cylinder cover from a Komatsu HPV pump (like this one). The control wouldn't function properly and was impossible to adjust. The pictures clearly indicate the problem - one of the small grub screw plugs got loose and ended up smashed against the cover by the very servo-cylinder it originated from.
I had to open a different (larger and standard-er) thread in the mother passage of the deserter plug to fix the unit, and although the steel is hard to machine, it's doable if done with care.