Not sure why things change when you push on the cap or housing. I just know that the main wear area, actually two, on a points distributor are the cam lobes which open and close the points AND the shaft bushings in the distributor housing. The tension of the spring in the points puts a load on the cam lobe, which in turn puts a side load on the distributor shaft itself.
The first time I had the cap off of out '72 Newport with the factory electronic system on it (later build so it was optional at that time), I was amazed at the "no side play" when I checked that with the rotor as leverage. That's when I figured out the deal about the side loading of the points on the shaft causing the bushing wear.
Back when points were all we had, they usually needed replacing at about 12-15K miles (about a normal year's worth of driving, usually). In the point sets, there was a little capsule of cam lube that went on the rubbing block of the points, which contacted the cam lobe of the distributor shaft to help keep them from wearing. For various reasons, like capacitor health possibly, one side of the points would receive/transfer material from one side to the other ("pitting" it was called) and was a reason to change the points.
There are NO secrets in how to change the distributor advance springs in a Chrysler distributor. Just that they are "buried" inside the housing, rather than on top like a Delco/GM distributor has them. Two springs, one heavier one with a long loop on one end (high speed advance) and a smaller one with a shorter loop on the end (low speed advance). The distributors are easy to pull apart to get to them, just that the distributor needs to be out of the engine to do it easily and quickly.
Which carb is on the engine? In any event, there should be a ported and non-ported vacuum port, each. The vacuum advance should be on the ported one (with very little vacuum at hot base idle). They normally start advancing at about 8" Hg, as yours does. Max advance at about 15" Hg, as I recall.
The neat thing about points is that if there is enough juice in the battery to cause a spark between the points, the engine will probably start. With an electronic box, it will take more relative juice in the battery to work the box to get a spark to the plugs. IF that might matter.
Last time I checked, the Cardone new distributor was a pretty generic unit, covering applications from 1958 and newer. That means the advance curve will be "will fit" rather than exactly matching what the particular factory unit might have been. Same with the vacuum advance unit. So you start with the base timing your engine spec's at (12.5 degrees BTDC of thereabouts) and go from there. If it clatters, retard the timing a few degrees and retest. Start with a full tank of premium fuel, for general principles. If it doesn't clatter at 15 degrees BTDC, then try some mid-grade and see what happens. If you need to back the timing back to 12.5, no big deal as long as it runs well (other than cost).
At 101K miles on the engine, it's about 20K past time to be thinking about a timing chain! The upper sprocket had the plastic teeth overlay and that's where things started to come apart as teeth could fall off and such. Might be worth the time to remove the water pump housing and the front cover to check it out! If it's "metal", then you can put it back together as the sprocket and chain have already been done. An "insurance" inspection, of sorts.
The earlier distributor housings had a rubber o-ring under the flange to seal against oil getting out from that area. My '70 Monaco 383 had a harder plastic o-ring in a slot below the mounting flange. Either style will work, if you end up with a reman/new distributor.
Being that you're trying to fix what somebody else had "fixed at", it can be frustrating to see what they did and THEN to determine why. Hopefully, the "why" can be easy to deal with!
Keep us posted,
CBODY67
