That Fixed it !!
I could write a book on my adventure to the resolution, but I will try and keep it short.
Attached pix shows close up of the solder "glob" at chip U53 ; the reel chip.
How it got there - a mystery. How the machine worked at all sometimes - a bigger mystery.
I could not remove the solder short and actually destroyed a land pattern in my attempt. So I had to remove the pROM chip 28-pin socket - yes un-soldering 28 pins and hoping not to destroy any components.
The other pix shows pin 10 and 11 securely soldered together "under" the socket. It was very easy to fix with the socket removed. Then fixed the cut land pattern and cross my fingers.
Powered up and it worked immediately - solid as a rock. Left it powered up for hours and every time I went to play, it responded beautifully - but it still took all my money ( so ungrateful ).
Thanks for everyone's help keeping me focused.
Dave