File the grooves with a small sharp mill file. Use a chainsaw file to make sure you have a nice radius at the base of the 'fingers'. Knock all the hard/sharp edges(stress risers) off. Go only deep enough to get rid of the grooves.
Someone wil prolly pipe up that you shouldn't file them, that it only makes the basket wear faster 'cuz the friction plates slam into the basket harder with the extra slop you created with the file. I used to believe that, but due to budget restraints in my roadracing days I would file my own with good luck.
Way I see it, if you only remove material to the bottom of the grooves you aren't ADDING any slop, just allowing the plates to slide smooth when you do actuate the clutch. I have done this on 11 customer's bikes since June with no complaints(on the contrary-usually praise for the clutch action) OR failures.
Mind you, I wouldn't smooth out a basket for a race/seriously high perf bike and the customers were always apprised of the options($$ basket-plates)/risks($$basket-clutch cover-plates). Time will tell for sure. I am thinking at the very least that they got away with plates this time and will have to buy a basket next time. The car guy who shares my shop building is into drag cars and he will spend an hour or more with a hand file making sharp edges into radii on his clutch packs, and he buys high dollar ones to start with.