Injection Pump Repairs - Lucas CAV DPA (5-09)
Section 5 - Fuel System - Group 05
B Series Shop Manual
Install a new o-ring. Replace special washer, if required.
Verify the shaft is still aligned and install the locking screw
Back Leakage Valve - Replacement/
Remove the back leakage valve and sealing washer.
Inspect the valve to be sure it is not stuck.