I'm having the same issue with Alt.Binz just stopping midway through a download and as you correctly pointed out there are a lot of "[T1] Response: 430 No such article" errors in the log.
However, when I try the same NZB through another program (like NZBGet on my NAS), using the same primary and backup servers, it is able to download and repair the files.
I would have thought that if it the same NZB was used, using the same servers, in any program the result should be the same, right?