Try taking it to an AC shop & pay for a 2-part deal: evacuate it now, then fill it back up in a few days. When you put it back together you can pull a vacuum o

Try taking it to an AC shop & pay for a 2-part deal: evacuate it now, then fill it back up in a few days. When you put it back together you can pull a vacuum on it, close it off and make sure it stays that way overnight. But you may still want to have a professional shop test with higher precision than whatever gauges you use.