Hello. I am very new to 3D printing. About one week in. I purchased a flashforge dreamer and it seems pretty straightforward except I am having one issue. Sometimes when I do a printing it will print the base and about 1/4 inch up and then all of a sudden the filament is just a bunch of strings. It does not do it on all of my prints. I have been downloading STL files from thingiverse and I was wondering if you guys believe this could be a problem in the download or if there is something else I should be looking at. I appreciate any feedback and I look forward to being a part of this forum.