When switching ON the game, sometimes it had very fast tempo music.

It happened 1 one out of 10 but it was very annoying.

So I used my frequency counter when it happened and I noticed that the 3.58mhz quartz ran at about 10.58mhz!

I changed it with a know good one but again it happened very often.

I was sure it was something connected to the quartz oscillator circuit and given that the resistances are difficult to be faulty I decided to change the cap C47  (33pF) with known good one.

After testing about 30 cycles of switching on and off the game didn’t develop again the problem

Game fixed.