That doesn't look like a Mugen to me...it looks like one of those knock-off cars. Mugens don't have those retainers on the outside of the upright ("knuckle"), they just have an alloy nut that holds the pivot ball in.
That said -- Once it pulls through, you have to replace the upright. They're pretty cheap and once it pulls through they'll always pull through again. Just get a new pair of uprights...and don't tighten it up too much. Just enough to get rid of the slop.