Both of my factory belt tensioners broke within 3 months of owning my SD4, so I created these more substantial ones in Sketchup. They use either the original brass inserts scavenged from the factory parts (with a slight countersink for the shoulder on the stock parts) or EZ-Lok 240-M3-BR inserts after reaming the holes out to 4mm (5/32"). Inspired by http://www.thingiverse.com/thing:705297 and the factory part, but ended up doing a model from scratch.I used M3x14 cap screws in the tensioner and M3x10 cap screws to fasten them to the frame. There are Left and Right versions with notches to accommodate the bushings that hold the rods in place. If you can't find the EZ-Lok 240-M3-BR inserts locally, send a picture of your finished part with a SASE and a request for 4 or 8 inserts to: ComputerSmiths Consulting, Inc. 151 Chestnut Street North Reading, MA 01864 and I'll send you some. They are 8 cents each plus $15 shipping and handling, so I stocked up.