I recently replaced the hot end on my M300 dual module for a Hot-End Module V3. Since replacing the module the soluble support material keeps jamming and coating the pinion. I am not having the same issue on the regular filament side. This M300 dual went 2 months with out printing while I waited for the new hot end to come in.
So far I have:
Disassembled and Cleaned the motor pinion. Cleaned full assembly before reassembling the motor per the extruder maintenance document on the support page
Tried printing a component that worked before the new module was installed.
Swapped to a different nozzle and cleaned the one that came with the hot end
Swapped to a new roll of filament to make sure the moisture content in the old roll was not causing the problem
as you have already excluded several possible causes of the problem and, most of all, replaced the hotend module tried a new roll of support material (I assume Z-SUPPORT Premium) - please, take some videos showing the extrusion issues and contact us via support form. Also, please, provide information if the problem with the soluble filament occurs only during the print, or as soon as you load it.
Forgot to reply to this thread on the issue I was having. Not sure what was going on but I was able to fix the issue by offsetting the platform -0.15. Leveling the platform was bringing the nozzle to close to the print bed