That's what I did. I have a set of 4 micro files (from harbor freight I think). One file is round and fits in the half circle perfectly and is very easy to take excess material off the half circle openings. I used another flat file to open up the notches on the chasis as well. Just remeber to take it slow, it's a lot easier to file, fit, file, refit, etc instead of taking too much of the board material off the first time.