I had a similar issue long time ago. With heat and metal dilatation, one set of points was grounding. The car would start missing, then would run on 4 cylinders and then would stop working all together. the car would then start again just by letting it cool long enough. I pulled all the hair out of my head before identifying the problem.

A blocked advance plate shouldn't prevent the car from starting. Assuming your issue was similar to mine, you may have solved it by fiddling with the points. If symptoms similar to the above start (re)appearing, you will know where to look.

Another issue I had a number of times on older MBs is the rubber/insulating washers deteriorating around the screw where it goes through the body, to which the points connect.