Praxis

I'm replacing some old Shimano cantilever brakes with Tektro CR-720s. The old ones had a plastic spring housing (that is apparently hard to find now); the new ones do not. Am I just supposed to install the spring without anything around it? Is this OK? It seems odd in that the springs are around a painted boss (wouldn't it rub?) and there's a bit of room fore/aft of the spring coils when installed.

I haven't inspected any cantilever brakes without any housing in the wild, so I don't know what they're supposed to look like.

Dan Burkhart 

A space is normal with the Tektros. It doesn't look quite right, but that's the way they are. Does not affect the performance.

Praxis

Thanks! Also, what's with this odd looking countersunk-head screw (upper right in photo)? The yoke already has set screws on each side to lock it in place, so why does one side have this odd screw sticking out of the back? For what it's worth, it's directly opposite the set screw on that side. Clearly the location the screw is in is not countersunk, so it's just strange.