Today I rebuilt a Power Director in a D17 series IV. The biggest porblem I have found through years with the power director is the intial setup. Once you have replaced all the worn parts with new parts, shim setup is critical. At intial setup, the service manual calls for .085in shim stack to be placed between power director housing and backing plate on  both high and low sides. A shim stack of .035in is placed between the low and high side backing plates directly in the center of the power director. Once the power director is installed on the transmission input shaft, there is some critcal measuring and simple math involved. Once you have done all the measuring and calculating, the service manual gives a real good chart of where and what shims are needed to be removed and replaced. One other critical part of this repair, is the marking of the two power director housing halfs. A simple numbering set works well. As a side note there are long and short shims. The long shims must be used between the two backing plates in the center of the power director. If a short shim is installed in this location, backing plate warpage will occur. You can't put long shims where short shims go because the long shims will hit the fiber friction discs and will go all the way down flush with the rest of the shims.