captured video from scanned 8mm film

I have an issue regarding the quality of captured video from a film scanner. Let me post you a background;

In early 2018 a got myself a small film scanner from Reflecta (may possibly also be manufacured as Wolverine) and with great help from Safeharbour11 in this forum, I managed to create a workflow creating a reasonably good result from scanning old 8mm film. In order to get an even better result I've got hold of a used but well kept professional scanner called Flashscan8 from a german firm named MWA. This scanner is outdated by todays standard but should be good enough for me to produce my scanned films on DVD. I use a JVC monitor with a SDI-connection to the scanner to check the running film and a firewire connetion between the scanner and my computer. I capture the film directly into Premiere Pro and here's the problem: The captured film looks out of focus and horisontal lines, or near horisontal lines, become jittery sometimes along with a color error. The film looks crystal clear on my JVC monitor (assuming its crystal clear on the original film) wich, to me, indicates that there's no problem within the scanning process itself. 

This is what I use:

Windows 10 pro 64 bit

Processor AMD Ryzen 7 2700x Eight Core 

RAM 32 GB

Monitor Eizo Color Edge

Flashscan 8 outputs 720x576 lines with 25 f/s and 25 Mbit/s on IEE 1394 (Firewire)

Though the scanning process is progressive, PP regards the film as interlaced when captured, so I change that in the sequence settings to progressive. I have tried to leave it interlaced but there is no difference to the quality other than when useing Neat video the picture is extremely distorted (from expected 4:3 to something like 16:3) but back on the timeline after filtering the aspect ratio is back to expected. 

Much appreciate some help.