Old dual temp bunker one end rises up in temp other ok need help!!

[Moe777]

I have a dual tip bunker running on a rack. I had a problem with one of the ends at 6 foot section flooding back due to a bad check valve I replace the check valve always well for 3 to 4 days then noticed it was going into alarm for up to three hours the temperature would go from -9.5f to 34f Then it would randomly come back down on its own or just as it was going into a defrost this led me to think that maybe the TXV power element was bad. I poured a little bit of hot water on the bulb. In the case started running again before I did this my suction temperature was 32f suction was 20psi. I figured the TX V had to be replaced as it was an old model and I could not get parts for it at my local supplier so I replaced it with a sporlan valve, manufacture said it was 330btu per foot of coil, so I built a txv for this. I adjusted my superheat about 7-5f The case ran great for 3 days then went back into alarm . So I wondered if my solenoid coil was dropping out I replaced my coil the next day the same problem happened as I was in the store I put my coil magnet on the solenoid nothing happened so I put some hot water on the TXv bulb once more case started to flow. Running out of stuff to replace in this case I remove the guts out of the solenoid valve and replace the ball valve as it was an old-style Canabalt that I have seen snap partially shut a times so I have eliminated/rebuild all things in this case including the fan snap disk yet this case still does the same thing does anyone have any other suggestions TXV bulb us mounted on 7/8 pipe at 2o clock ish bright tight and clean, rinks great when it runs, coil is always Clear,