1976 Trinitron flickering blue color

[Duke1921]

Hello everyone, I am new here. I have been a master electrician for over 30 years but am relatively new to electronics repair. I have an extensive retro console/game collection and have recently gotten interested in electronics repair. I’ve recently acquired an absolutely beautiful 76 Sony Trinitron and am currently attempting to make some needed repairs/adjustments. I already replaced about 30 electrolytic capacitors which have fixed a few of the issues but the one I am trying to figure out now is the blue color comes in and out randomly. The service manual suggests it may be one of three components: a transistor, a diode and an amp. Two of these components are under a shield that I am trying to avoid removing. Anyway, just thought I’d get some insight from some more experienced folks. Any thoughts? Thanks so much.