Yes, my 12 inch LB mirror - 3 years old has one place where there is a 5 mm circle with no silvering on it. Light passes straight through!!
Someone on this forum suggested that I put a dollop of black paint on it to try and stop the hole growing. That has seemed to do the trick.
Haven't noticed any drop in performance, but not too impressed with the quality. As you say, maybe Meade quality control was up the gurgler in those days.