Pro tip. Not sure if other experience this... but I had a LOT of issues getting the hard line seals to seal again after removing them for various reasons (including installing this gauge)
@marshallhirt
@rappert
Get some basic valve lapping compound. (I ordered a small container off ebay, already had some for other purposes) If the seals fail to do their job on the end of the hard lines, just use a sparing amount, push the seal up against it's mating surface (basically just push the end of the hard line fitting into the hole it goes into), and twist if back and forth so the lapping compound can do it's thing. When lapping you want as much uniform surface contact as possible. Basically trying to smooth and even out both sealing surfaces against eachother. Then make sure to clean all the compound out.
My seals were very hard and even with tons of torque didnt want to seal till I did this... no more issues, even with multiple disassemblies. Just some advice in case yall run into this issue too