To avoid serious injury follow all warnings and instructions in the manual. Wear appropriate personal protective equipment.
The B dose has overshot, forcing an A dose that, when combined with B, is too large for the mix manifold capacity.
Repair the valve.
Check for pressure pulsations:
See Ratio Low Error and Ratio High Error, R1 and R4.
It may be necessary to restrict the flow rate through the component B dose valve by adjusting its hex nut.