I've placed a support ticket with the vendor so they can tell me what's ok or not from a warranty perspective, we'll see what comes from that.
There should be a system-restore option on the preinstalled OS, but I can't figure out how to get to it. Good news is that everything except the OS is on the separate 500 Gb drive so that's a relief.
But partition Manager Boot Disc was new to me. Good tip, thanx