Minoura Kagura LSD9200 Calibration

[TropicsTourer]

Hi there, Have been using the Minoura Kagura LSD9200 for about six months now. Its reading 10% more watts than my Assioma Pedals at ~200Watts but then seems to align again at ~700 watts. Have done the spin down calibration on zwift but not sure if it's actually doing anything despite the test saying complete. Some Metrics would be nice here Zwift! Have downloaded firmware updates for Kagura and installed.
I usually run Sufferfest, all on bluetooth and have a Wahoo Kickr that has no such issues as I calibrate that on the Wahoo app. (Kagura wont connect to Wahoo)
Any suggestions for a free app to calibrate the Kagura apart from Zwift?