I have gauges but these small cap systems are sealed, but yea I do have a few bullet piercing valves. These systems being so small must have a very precise refrigerant charge, while I regularly gas up cars and I’ve gassed several refrigerators just by monitoring low side pressure I think I’ll take this to a professional so they can weigh the refrigerant precisely.You have gauge ports? Gauges are pretty cheep on EB. That will tell you what’s going on. If not you can buy the piercing ports to convert.