The issue is most likely that the needle(s) have clogged up. To fix this do the following:
- Pause the active bioprinting process.
- In the “Utilities” menu, turn off the print head(s).
- Remove the cartridge(s) from the print head(s) causing the problems WITHOUT removing the air preassure hose.
- Remove the needle of the cartridge(s) and replace it with a new one of the same type.
- Carefully place the cartridge(s) back into the print head(s).
- Resume the bioprinting process.