A small plastic tie-off mount is used with a zip-tie to keep the power cable from being accidentally pulled out. The plastic fins of the cable tie-off need a little reinforcement to prevent slippage. Hot-glue has been used until now. I designed a little clip that fits snugly on the back-side of the chassis and tie-off. The clip allows the tie-off mount to spin but not be pulled out. Neat. Once I had the design dialed in, I made enough to share.