Timing issues - Advance questions

Yeah, my car still pings (it has the below done to the engine, which is basically nothing, and with a 9.5 compression ratio it pings with 91 at times, with 87 pretty much always... it should run fine on 87). This is with my carb rejetted to run on the richest setting the adjustment kit will allow (also a reason for fixing, the richness has caused my mileage to dip into the 8 mpg zone).

I think its still the advance, because the intial timing is only about 8 degrees. I don't have anything to measure total timing, but because the pinging only occurs at mid to high rpms and I can "throttle my way through" the pinging (ie it will ping from say... 50-85% throttle and after that it will stop), I believe its the advance.

I was told that the mechanical (inside the distributor) portion of the advance (I'm using a stock Ford vacuum advance) has some parts that can rather easily and often come apart and cause problems like this... can anyone reiterate what these parts are and how to identify and fix the problem? Also, I don't know if my vacuum advance does, but I've been told that at least some aftermarket ones have tiny screws in the vacuum port that can be adjusted to fix vacuum related issues. Can anyone also tell me the procedure with that?

Thanks a ton.

isn't there some sort of rubber peice that can come off off the mechanical parts under the plate that holds the points (on one with points, since mine has a pertronix)