Scramble repair log

Interesting one this, graphics were doubled up, wrong tiles used and the text was garbage;

I quickly and correctly diagnosed that Bit 0 is stuck low on reads/writes from screen/object RAM.  You can tell by looking at the scoreline;

I started to look at the video RAM addressing circuit, found a LS157 Multiplexer at 4G used to access a bank of video RAM with pin 9 stuck low.  Removed, fitted socket and new LS157;

Now working 100%;