If it's just a wheel alignment problem you can grind up the lower
slot. With plate fork ends I've just used a file for a couple of
minutes. If you are bending the blade into alignment you should
(ahem) use some padding on your lever. Failure to do this may result
in a broken or dented blade. If the fork won't yield easily, it's
hard or belongs on the grocer's bike and probably best replaced.