I just bought a Warwick Corvette Standard fretless 4-string for $400

. It's in great shape, but I would like to put on some Fender stainless flats (9050M, .055-.105). I did a full setup, but noticed that the 9050's are a little too big for the nut slots (particularly the D & G strings). The bass comes from the factory loaded with .045-.105 Warwick strings. After reading the owners manual online, it seems to say you can adjust the nut with the allen screws to accomodate larger gauge strings (without filing). It does not say how to do this however

. Anyone care to help me out with this problem? Thanks.