I hunted through my odds and sods draws and found a silicone Noctua case fan mount that looked like it may do the trick. I removed the frame lug and pushed what was left of the old bumper out, pulled the silicone fan mount through and low and behold it was perfect. Even kind of clicked into place as the rubber ledge popped into the hole and seated itself. Trimmed off the tail and it works like a charm. Frame locks up with no wiggle and feels really solid.
You can purchase packs of these silicone fan mounts online in varying shapes and lengths for a few bucks. Anyhow, hope someone may find this useful. I was bloody happy to solve an annoying problem that had bothered me for ages.
