As a general rule, the shaft area of your Graco T3 Pump should be checked, cleaned and lubricated every three to six months. When you get a new T3 Pump and during these checks, run about 20 gallons of material. Afterwards, tighten the packing nut by hand and then use the included spanner wrench to tighten an additional 1/8 to 1/4 turn.
PMC GHO, IPM OP series, Graco T2 Transfer Air motor performance
After use, the transfer pump air motor starts operating sluggish and leaks air. This is generally due to deforming (wear) of the upper reversing spring and the upper air valve gasket. You can notice the spring wear off in two ways. The first being the pump fails to return to the down stroke and secondly the pump will pause momentarily when reversing to the down stroke which appears as a cavitation type action. In this situation, hanging the spring is the best solution, but when in a pinch, stretching the spring to its near original length can get you through the day.