What you describe sounds similar to an issue I had with an HF-G30 a couple of years back. I made a video demonstrating the problem and emailed it to Canon Service (Canada) to see if they could give a tentative diagnosis. But they advised that I would need to send the camcorder in for full assessment. I decided it was not worth it - the camcorder was long out of warranty. I considered opening it up myself to see if I could pinpoint the source but thought better of it. Sold it as 'For Parts/Not Working' and put the proceeds towards purchase of an HF-G40.
Never found out the cause. Only thing I can recall is that the last time I used it before the issue started was at a sporting event where I had it mounted on a heavy duty Hague C-Bracket with a Manfrotto 323 RC2 quick release adapter and 200PL-14 plate. Being right handed, I would on occasion hold the camcorder by the hand strap whilst adjusting the on-screen settings with my left. I wonder if the added weight of the L-bracket (plus LED panel) leveraged stress on the camcorder tripod mount and chassis. That's the only thing I can think of.
This is the original video I sent to Canon Service demonstrating the problem:
HF-G30 Screeching Noise
(@Moderator - please don't delete the video. It's important to this discussion. Thanks)
I would suggest sending your HF-G50 in for service while it's still under warranty. If it's the same as the problem I had with the HF-G30 it's not normal and will likely persist.
