This is why you don’t buy cheap J-head clones…
I’ve ordered a J-head today from http://hotends.com for the purpose of reviewing and benchmarking with the filament force sensor.
I’m hoping to formulate a standard range of tests to use for benchmarking flow rate, temperature and force; The J-head original should be a good choice to benchmark other nozzles against.
I also, did a damning J-Head clone Review:
http://airtripper.com/1236/j-head-mk-iv-hot-end-clone-design-quick-review/