Originally Posted by
memepat
Light bulb goes off. Never thought the grooves in my mat might be causing the rotary blade to get nicked. Wow. Maybe need a new mat or condition the old one. Thanks for the tip.
No, the grooves don't cause the blades to get nicked... they just open up under the pressure of the blade and do not provide enough resistance behind it to produce a cut. Your skipped spots in your cut can be caused by a worn out mat, even with a perfect, un-nicked blade. Flip your mat over when it gets like that, and wear out the other side.