I was having the same problems with the needle bar hitting the side wall of the tubes when using my DK whether disposable or ss and making a lot of noise(and chipping on the disp. which is def not good. Could have tattooed plastics into the skin(thankfully, I discovered this before working on somebody.) After trying different rubberband setups(more tension/less tension ect... I found that needle runners helped a tremendous amount on my DK, but I do still use a rubberband on there as well. More for piece of mind than anything. I place the needle runner about halfway down the bar slight bend on the needle at the solder point and now it runs smooth and silent as can be. I highly recommend them. I'd say give em a shot. I was at the same place with my DK and was about to call it quits until I got the needle runners. And man am I glad I did! Its the only machine I use for packing and shading now. And if you don't like em, you'll just be out a couple of bucks. Good luck.