3-handle tub and shower diverter repair problem

Problem: Water runs from the tub spout even after I turn the shower diverter handle as far as it will go. So, I removed the middle compression type diverter assembly and replaced the rubber washer under the end screw. I soaked the assembly in vinegar and scrubbed it with a toothbrush to remove the green and white build-up. I did not change the "hard yellowing" O-ring because the person at Home Depo told me I didn't need to (and it seems almost cemented on). Lastly, the middle stem piece will completely turn inside the locknut part when I hold the assembly in my hands. However, each time I put the complete assembly back into the wall, the diverter handle will only turn 3/4 of the way. Do I need to replace the entire diverter assembly to fix my problem? Please help!

Sounds like you've messed with the diverter stem long enough. I would just replace it and move on to something else.

I'm guessing that on your diverter stem that the washer you replaced when closed keeps the water from going to the shower but look at the stem real good because there is a seating place back towards the handle when you divert to the shower and it may be that o-ring you mentioned. You should be able to see where the stem seats in both directions. What do you have to lose if you replace the o-ring?

This is important : Don't count on Home Depot to have a lot of good answers.