Professionally, in Wellington, the only repair agent that would take my old computer monitor in for repair was:https://yellow.co.nz/y/advanced-televis ... ame&c=9554
Around 5+ years ago he diagnosed and repaired an IBM 5151 display for me. He's a guy who really knows his stuff, and correctly diagnosed the fault just from me simply giving him some symptoms.
Price was good, and hours on the job showed he really knew what he was doing.
The downside was communication e.g. oh give me a few days really meant give me a few weeks.
This doesn't seem to be unique to him though, one store that agreed to help me on one occasion has had my PS/2 50Z power supply and phone number for 3 years now.
Smiling, being polite, talking honestly with them, letting them know that you're happy to pay and why - didn't make any difference - just generally if it's not a $3000 TV, nobody cares.
In the end I just decide if a monitor is worth it, and if it is, repair it myself.