I'm new to CE and have no experience troubleshooting. Doing some method development and everything was running just fine. Someone else used the instrument for a few weeks and when I came back to it there was a ton of leakage current. Took the whole thing apart, cleaned electrodes, insulator plate, and pre punchers of salt buildup. Now when I run blanks the current drops from 50uA down to about 25uA despite voltage and temperature being constant. When I try to run a standard (trying to figure out a good ISTD), the current drops from 50uA to 0uA after about 2min. Leakage current stays around 0

Buffer is 20mM phosphate, running voltage is -20kV, standards are 100ppm anion in 20mM buffer solution. Agilent guy was in today and had no idea what was wrong, only other person in the building with CE experience is my PI who also has no idea what's wrong.