What SN? A5 SMD or TH ? Beware as hrs can be changes at CAL.
Have full serv man for the serial range?
Usual drill:
0/ IF A5 is SMD check for corroded SMD cap damages
1/ Check all PSU V/ripple at U119 header on A1 bd
2/ Probe CRT hor pins or HOR amp output for large DC bias.
Bon chance
Jon
Jean-Paul