Is the water supply pressure constant and sufficiently high?
Check water supply / pump.
Are the correct nozzle, lance & gun being used?
Adjust the air reducer setting, if necessary. His applies to foam only.
The injector draws insufficient agent during foaming / disinfection.
Check the suction lance, restriction and injector for contamination.
Are water and/or compressed air coming out of the overflow valve?
Replace/ repair the non-return valve in the satellite.