Atari 65XE screen brightness flicker

My Atari 65XE screen display started playing up earlier today. I was playing the game "Mr M" when the screen brightness started fluctuating or flickering. Various times, the screen went slightly darker, before quickly returning to normal. I played another game "Spindizzy" to see if the effect was still present and it happened again.

At the moment, I haven't taken any further action to find the fault, apart from unplugging then reinserting both the monitor and power leads. I'm using the 65XE with a SONY KV-14V5U or KV14V6U VHS video combo TV plugged into the SCART socket. This model came out in 1997 and was seen in the classic TV series "Goodnight Sweetheart" in Gary's shop. Obviously, the 65XE is at least 5 years older than the TV.

I've got another TV I could use it with, but haven't tried that yet. I just wondered if there's any action I could take to fix this situation before it gets worse or something breaks down.

I've had various electronic devices break down recently, so I'm trying to learn more about electronics so I can fix some of them without paying someone a small fortune to repair them. I know that I shouldn't try to repair the TV myself, otherwise I could get a fatal electric shock.