Ok, so I’ve managed to print what I previously was not able to due to grinding by disabling retraction and setting the fan speed to 50%. It’s much better, but still 2 to 3 grinds on a 1 hour print. However, I’m still having to watch it so that whenever it starts to clog up again (starts grinding) I hit pause and do a little dance of lowering temp to 1/2 and taking out filament, cutting it off, and putting it back in. Then resume… This is pretty annoying so going to try a 40mm fan + duct on heat block next. Hope that works, or PLA is going to be unusable.
Here is an idea: why not have an opto wheel (like old mice wheels) or similar to read if filament being pulled in matches up with requested extrusion… if it is far enough off, then this could be a ‘grind detector’ that can then pause printing for user intervention. This would be very handy on longer prints with experimental or finicky materials.