I've recently got the Gmax XT+ and have set it up printing the filament that came with it. The spacers all seem as they should be, I have figured out how to make the first layer stick and have had no problem getting subsequent layers to stick as well. BUT, on vertical surfaces I get, instead of a smooth finish, a series of equally (vertically) spaced ridges (about 6mm apart vertically) on one side, with corresponding grooves on the other side. Can anyone suggest anything? It's the regularity of the ridges/grooves that is so striking