It appears that putting the filament in a freezer bag with a couple of silica gel packs for a few days fixed the brittleness.
So I went through the calibration steps at https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+4:+Calibration/40 and the BLtouch part. I got to the part of printing the test cube, the first layer still isn't sticking properly and I'm not sure the compensation is working, if I look at the first layer it's trying to put down, some of the areas are laying down ok but others look like the nozzle is too close to the bed. I don't see the Z axis screw moving at all when printing, it gets most of the way through the layer, but then a part of it either doesn't stick or comes unstuck and gets pulled by the nozzle and takes the rest of the layer with it.
I ran the mesh bed compensation to generate the height map and it looks ok I think, I did all the flow rate and esteps calibrations, the bed is as level as I can get it.
I tried Baby steps and it doesn't seem to be helping, I'll keep messing around with it, but some help would be good. Let me know if you need me to post settings or anything.
I'm prinintg PLA at 210 with a bed temp of 60 at the moment, the first lines that get printed on the side from Cura seem to go down fine, but when it starts printing on the bed is when things start to degrade, this is on the creality glass bed as well.