Dang sorry for leaving you hanging! I didn't have my notifications turned on for some reason... For what it's worth & if it's not too late; Yes, I just drilled it out and measured the distance and cut as precisely as I could nearest the hobbed bolt and then beveled the top end of the tube to mimic the shape of the gap where it meets the feed tension bearing (or whatever it's called) with a razor blade. It was a ton easier than I expected.. I'm not sure if it's for sure the reason I've been having luck, but it works fine with flex filament now.. I definitely wish I'd have tried the oiler first tho.. If you haven't done it, I'd print a filament oiler and that may be all you need.. & if you want any kind of luck or decent looking print, it has to be done VERY SLOW. Hope it helps and isn't too late!