Hi all, I have an issue with one of my UMO+. I have 7 UMO+ machines and all of them are exactly identical. All of them have an E3D hotend setup with 0.6mm nozzle and dual 40mm cooling fans. Also the machines have an upgraded extruder that I've designed myself, which is way more powerful than the stock UMO/UMO+ one. Firmware and firmware settings are identical as well. The extruders use slightly different steps per E (less than 1% difference) after I calibrated them, I don't think this difference has something to do with it. The problem I run into is that one of the newest machines is acting weird. Somehow I can't run the same gcode file without having retraction issues. Normally I use 4-4.5mm retraction for Colorfabb PLA. But this machine somehow needs more than 6mm of retraction (which is pretty heavy for prints with a lot of retraction), or else a lot of blobs appear on the print's walls. I regularly season the filament with a drop of olive oil which works well against jamming issues, but this doesn't solve the retraction problem on this specific machine. Also I swapped extruders, which didn't solve the problem as well. Does anyone have any idea what could cause this problem? Would be great if you could help me solve it.