814 Repair Manual — Volume I — Page 116

4. To begin, some bubbling may occur, due to the action of the diaphragm. Maintain the pressure for a few seconds. If bubbles of air escape via the hole for the control lever at «f», it means that the diaphragm is leaking and the lower body must be replaced. If air bubbles escape between the contact faces of the upper body and the lower body at «e» or round the securing screws at «d» it means that the joint faces are defective or that the screws are 2092 not sufficiently tight.