3 Unscrew the valve plug and withdraw the spring and plunger. Check both for signs of wear or damage and renew them,
if necessary; note that the spring should be renewed if there is the slightest doubt about its performance. Polish away any burrs or raised
edges from the plunger and check that it is free to slide smoothly, but without play, in the pump body.
On refitting, renew its sealing washer and tighten the valve plug to the specified torque wrench setting.