My backup is (and has been) sad for a while, but I checked again and still I find no obvious vfd damage. So either the epoxied joint leaked and it lost anyway or there's a fuse out somewhere.

The question is, would it be smarter for me to just pay someone to fix it, or would the need to ship a spare vfd with it (I do have one) for potential replacement dictate that I should try more self-diagnosis (which I don't really have time to do at the moment)