I have a Panasonic NV-HS830. It seems to be working fine, except the right side audio on recorded playbacks (I have no VHS originals to test!) has terrible crackling. I've uploaded a video so it can be heard.
Where is the audio record and playback heads? Are they also on the drum, or are they separate? I've done the clean sheet of paper head clean trick already, I want to examine the audio heads separately if possible.
Heads for hi-fi audio sit on the video head drum. Heads for normal audio sit on the A/C head, which is stationary and is positioned to the front/right of the video drum. I presume this is from hi-fi audio though, as normal audio is mono (outside some broadcast VCRs and a few 80s models.)