It would require your TV tech to know a lot about the schematic or part testing. The time the tech charges can easily cost more than a board so boards are swapped after a diagnosis.

As a TV Tech you would have the service manual and followed it's guide. If you are hoping that a TV tech will guess the right part, that is just hope and not reality.

Here's the tip from my friends in the business. If you don't know which part is bad, replace the cheapest part first. If the parts cost more than the device, replace the device.
Bob