Hello Roberts123,
Sorry I don't know your name.
The problems you have is two fold, more than likely you have dry joints (cold joints in the USA) on your boards, if you can solder correctly then check all the boards from the power supply upwards. The problem will more than likely be on the Selector Logic Board.
All the boards on your jukebox contain some CMOS chips so static precautions must be followed.
The other double stiking of the keys is down to the fact that the switches on the keyboard need replacements.
Regards
Alan Hood
ami-man
UK