shower diverter valve leak

First,this is not the kind of valve diverter that's on the bathtub spout. I have 3 valves in line with, of course, the middle being the diverter. it's a Sterling brand. Problem: Replaced all 3 valves. Plumber at plumbing supply house told me that the adjustment nut at the front of the valve does not need to be tightened real tight as most people think. He told me to tighten diverter valve with water on until water no longer comes out of spout (as the shower is running). tried it but it didn't work. Then realized that i needed to follow the same procedure FIRST with the hot and cold. seemed to take more than just a snug tightening on all 3 valves. not sure if i did it right. there is still a small amount of contstant leak while shower is on but it's negligible. Would like to know if i did this right or wrong. any help appreciated. thnx,eric

ws he really a plumber.

Either you misunderstood his instructions or he was not a plumber. You tighten all three stems as tight as possible, but you do it with the stems in the full "OPEN" position so they do not jam in the valve so they cannot be tightened properly, or damage the valve's body. You can loosen the packing nuts to make the stems turn easier, as long as they are not so loose that water leaks around the stems.

Thnx for the help. much appreciated. eric