The fuel pump, removed from the engine immediately after receipt at the works, was sent along with the injectors to the fuel-pump repair shop (first image). Here was a "clean" room, 35ft by 27ft, with fitted benches and cupboards on each side and the calibrating machines and storage racks in the centre. The floor, benches and racks were linoleum covered. To secure maximum cleanliness all pumps and injectors were dismantled and cleaned before being brought into the "clean" room. Each set of cleaned parts was delivered in a tray provided with a socket for each component. Pump plungers and cylinders were first tested for rate of leakage on a Merlin comparator, and injector valve seats were ground and lapped on a Merlin Servicemaster.
Each bench assembly station was fitted with an air-pressure cleaning nozzle discharging into a fixed tundish. The tundish was connected by trunking to an extractor fan, thus ensuring immediate removal of dust and foreign matter. Plastic hoods were used to cover all equipment until required for immediate use, and on the benches were roller-mounted canvas covers for the overnight protection of work in progress. For pump calibration there was a Merlin Calimaster and a Hartridge test machine (second image); and on the injector bench were three C.A.V. hand-pump test units.