:welcome: to TBN
Post a pic or three of the cutting pattern. May be able to decipher what is happening.
Some thoughts, that will cause strips. One is a bent blade. Check that all the tips line up when rotating them by hand.
Two, that on blade is on upside down. But this will show up when checking the tips for a bent blade.
Three, that one of the blades has a dull edge, which can happen if getting hung up on a rock or concrete slab.