OVE-20 TXV conundrum

This is an AC application but I feel ill get the beat answer here- as I normally do. Two 20 ton externally equalized OVE-20s feed a single 40 ton evap. Had an undercharge condition. My pecking order is charge to an appreciable amount of sub-cooling then check superheat. Is the most logical to me- so I'm starting to feel comfortable with the charge. So I check my superheat at the evaporator outlet. Huh- both all over the place- absolutely will not stabilize hunts all over from excessive to flooding. So.... before I proceed here let it be known that I preach and am very adamant about NOT MONKEYING WITH TXV-. But I this case I had to get to the bottom of things. I monitored things all day. First thing verified stem was at factory (half way) setting for step one. No change. For grins I closed it all the way- no change- still flooding - then starving - flooding then starving back and forth... Now how in the hell can I be flooding with the stem all the way front seated for test purposes and why do both do it- two txvs feed single coil. Obviously the power head is opening the valve- hence the flooding- but my main question is there any rebuilding the guts- I don't think these larger valves have a cartridge like the smaller ones. Also it doesn't feel like there's any stop at front seat or back seat- just stem turning almost as if it had been reefed on at some point I would expect a significant stop or resitance at full open or close but stem just spins- does retract and extend but doesn't seem to stabilize superheat. Just weird that both are doing it. But one thing I've learned and am quoting another user here is in this business "depending on age discount nothing". Words to live by. So does sporlan offer body rebuild kit or is only the power head replaceable. Seems like the body does come apart.