Have you worked that out, or are you guessing? The one I detailed above was the first one, picked totally random, that I looked at, and that had multiple issues from a first inspection.
Which ones?
I've looked at two (9M20 and 9M22) that pass through Southbound, just using tomorrow's timetable there does not appear to be any freight to either side and they likely could run a shade earlier from Newcastle and call at Chester-le-Street without significant disruption. The problem is that they appear to use pre-pandemic slots, so there may be more wiggle room as well if a Nova 1 can be guaranteed.
Unfortunately, getting multi-operator information at one time and for multiple points is rather awkward, I had to do a lot of jiggery-pokery involving the various freight junctions just to find the (apparent lack of) freight paths around those two (Birtley Junction and Tursdale Junction being the key points). Searching King Edward Bridge south does not show a lot of freight trains, even for all tomorrow, either.
As a slight aside, my last pre-pandemic (well, early pandemic) journey was Newcastle to Chester-le-Street and it was a Class 185 in a slot that looks very much like those that are calling Chester-le-Street in the current timetable. So there may be wiggle room if they are Class 185 slots run with a Nova 1.
(1643 ex Newcastle, arrive 1652 IIRC)
I have looked at a good number of them. Not all, but many of them. I have been fighting the case for a better service at Chester le Street for a while now, and looked into this for exactly the reasons you mention.
Platform 3 is vacant the entire time that the TPE unit is in Newcastle station, and the route over the King Edward Bridge is also available.
That is a large part of the problem with getting trains to call at Chester-le-Street as the timetable stands, perhaps the best short-term campaign point would be to seek better use of Nova 1 performance (where one can be guaranteed) in slots marked as Class 80x but actually timed for 185s.
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As a slight aside, many of the freight services seem to be heading between Tees-side and Scotland. Could they be put on the Durham Coast line instead?