I experimented with this briefly in the past. What I did was I bought a composite/S-video to component/RGsB (sync on green) converter to get the OSSC to recognize the signal. The OSSC can take RGsB from the component inputs. The problem is, like you experienced, it loses sync frequently. I think something like a time base corrector (TBC) might address that problem and output a cleaner picture, but I’m not curious enough to spend over $300 to experiment with it! Maybe I’ll find a used one for cheap some day, but in any case, losing sync was also one of the major issues I ran into during testing.