I have been using 3d printers for about a year. Most of the time, the spool runs smoothly while printing. But sometimes, the filament just gets tangled on the spool (crossed with other coils) and the printing cannot continue. It's a big headache as I have to withdraw the coil, loosen several coils and rewind, and start to print all over again. When this happens, it'll take much time to deal with it, which is so annoying. Can anyone offer some tips? Thanks a lot.