I noticed that some articles were very incomplete downloaded, e.g 22, 39, 23 or 24 of 66 blocks (even with 5 retries). It were yesterday's articles, so rather recent. However grabbing with GrabIt gave no problem at all (same time, same system, same pay server (Eweka)).
Update: Sorry for bothering and trying to blame Alt.Binz. Mysterious things were happening. After some sleep I continued with GrabIt, but got only those famous txt-files.
With a freshly created nzb-file Alt.Binz is now behaving as normal. With the new nzb also GrabIt is downloading completely, but at only approx. 5% of regular speed.
I give up, it's too difficult for me.