My Robo 3d r1 plus printed 3 or so things and then started having extrusion problems.. I noticed the hobbed bolt was worn on one side, so ordered one off eBay. The bolt I received had a really narrow band/hobbed portion and didn’t want to line up exactly even after shimming. It now stops extruding after the first or second layer. Where can I find a better hobbed bolt? I upgraded the extruder with the print4d solid upgrade kit and purchased a titan as well, but couldn’t print long enough to make the required parts to install the extruder. I purchased this R1 Plus refurbished from Robo 3D and thinking maybe I should researched my choice a little more first. I’d like to get this one up and going, but after many hours playing around I am at my wits end. Surely it is just the hobbed bolt I ordered and would like to try replacing it before I toss this Robo 3D to the side and order a different printer.