You go out on the bleeding edge, and take one for the team.
I have never had the problem, but sanding a spacebar might be a great idea.
Probably hard to turn around, since the slots face a certain direction on both parts.
The good news is that standard Model M spacebars are common and cheap, if you screw up.
I am using my heavily modded Model F-122 and it has a unique spacebar that is very hard to come by, so I don't dare.