Sorry that I failed to answer your specific question about the meaning of the numbers at the bottom of the older Timex dials. Normally, for me at least, the only really useful information is contained in the final four numbers. The last two numbers are the year of manufacture, thus one ending in "71" was manufactured in 1971. The two preceeding numbers are the movement number. That number can be very helpful if you have a movement that's not working and you want to replace it with one that's good. So, if the final four numbers are 2371, you have a watch which uses a number 23 movement and was manufactured in 1971. The numbers to the left of the last four numbers are the model number. Once in a while you'll see a letter "A" following the last two numbers. I have no idea what that means.
From my very limited experience, I'd say that a watch that runs irregularly with frequent runs of a few seconds or minutes and then stops needs cleaning. The watch repair books and videos I have say that the problem is probably some sort of dirt on a moving part that keep coming back around on one of the wheels and the watch slows or stops when the mechanism hits that dirty spot. My own experience has been that when I clean the movements thoroughly (I use an ultra sonic cleaner), most of the watches that had been running irregularly run perfectly. If the irregular running isn't corrected with a good cleaning, then you have some sort of mechanical problem.
Also, you can find old Timex Service and Repair Manuals for sale on Ebay from time to time. I've purchased two that way for as little as $6.99 each plus shipping. They usually cover Timex models produced between the early 1960's and the mid to late 1970's, which is a period that covers the time when most of the old wind-up's, automatics and the early electric/electronics were made. I've found that I can follow the step-by-step service proceedures outlined in those manuals fairly easily.