I found some posts an video talking about “unattenuated RGB sync line” and that some devices can damage the OSSC.
I recently got a new Amiga (A1200) and the OSSC breaking down coincided approximately with that, after having used it for 2 years with an A500 without problems.
Anxious now to get a new OSSC if that will break too. In that case is it covered by warranty? Im not using some obscure arcade board or someting its just a standard A1200
Relised now this post is in the DIY forum, but my OSSC is bought complete from videogameperfection.com in august 2018