I have two UOs, in each the bowden tube pops out of the hot end isolator coupler, disrupting the print and causing clogs. The tube is all scratched. I tried snipping the tube of one, it still pops out ... the coupler must be damaged, right? For some reason, Ultimaker's online payment service is unale to accept my payment via credit card. Does anyone know of an alternate source for these parts, preferably in the USA? Please advice. Thanks!