Answering this here on the forum, because it's actually a pretty common problem. And not just on a TBC-1000, but TBC's and video gear in general.
What you're running into is a power-related issue.
I had a few TBC-1000's for quite a few years -- until 2006, when I moved. The new location caused vertical bars to travel horizontally acoss the screen -- completely power related. Being in a rush, I replaced them quickly with AVT-8710's, which had no such issues. I had work to do, could not delay any longer.
Had I spent more time, and had I known what I know now, simply changing out the AC adapter would have done the trick. I know the adapter how have, for obvious reason, works perfectly. However, you exact location may have electrical issues. For me, the issue was a voltage overage, a constant 126V+ on the meter. It was within allowable levels, but it's several volts above average. New construction, TVA, new lines, close to the power relay, etc --- I get juiced here.
Does the TBC-1000 have a fuse inside? I don't remember -- sometimes those are guilty, too! The Elite Video BVP4+ proc amp has that exact issue sometimes, noise from faulty fuse.
My current AVT-8710 in use this very minute has an issue identical to the TBC-1000 error you've run across. When this AVT-8710 heats up, or has been left on for too many hours, it can show that problem.
Other times, the AVT-8710 just "goes bonkers", and you have to unplug it for a few moments, then plug it back in. It forms a honeycomb-like grain noise, seen easiest on a blue screen from a JVC VCR.
Cleaning the connectors with a non-cotton swab and some alcohol sometimes helps too.
However, in yet another experience, I've found that the s-video and/or composite cables can be at fault -- especially if you're doing a "crossover" connection, where the TBC input is composite, and the output is s-video. You're best staying s-video or composite throughout, from VCR to digital capture/recording device. Consider regular wires, not the fancy "gold" ones, for tests. When you're convinced it works right, try the cables you think are best. Sometimes this thick and expensive brand-name cables are worse than the pathetic noodles they give away for free. Go figure.
Hope this helps.