Disconnect the turbine from the hose to see whether there is sufficient water supply from the hose. If there is not enough water supply, most likely causes are clogging in the hose, poor connection, lower water pressure or malfunction of the dental unit.
Attach a coupling joint to the hose, and then run a test. If there is not sufficient water supply, you’ll know the blockage is within the coupling joint.
Clogging caused by water scale
Insufficient water pressure caused by loose coupling
Connect a turbine body (without a cartridge) to the coupling and run a test. If there is not sufficient water supply, you’ll know the blockage is within the turbine body.
Clogging caused by cruds around the water hole
Clogging within the water circuit of turbine body
If you see sufficient water supply at Step 3 above, then clogging should be in the cartridge.