I know exactly what you are talking about. I used the same trick on a Roland SP-300V a few years ago using Roland's ColoRip software and it worked great. I don't think Flexi gives you that option. You can try printing unidirectional instead of bidirectional. In the Driver Options window in Flexi, you can try increasing the Interval Time thus making the print head pause before moving again. You can also try 1440 X 1440 dpi printing. That's a pain because it's so slow, but it might help. In the service menu of your printer, there might be a way to slow down the carriage, but I doubt it. And, be sure the head is in the low position.