JVC HR-S9911U brightness bug with TBC/DNR
 

I usually run my VCR through a frame sync and/or proc amp, which apparently have been masking a problem with the Digital TBC/DNR circuit. I made some recent captures straight from the deck and found the gain pulsing about 2–3 times a second on an intermittent basis. When I switch off TBC/DNR, the problem goes away. It's evident with different tapes (definitely not Macrovision) and I see it on my analog waveform monitor coming right out of the JVC. Does this sound like a component problem, such as a bad capacitor? I have owned the unit since purchasing it new in 2004.