I tried to change the blade on my kapex and the blade stop is not locking the blade. I tried to engage the button in multiple positions and still nothing. The knob turns correctly and locks the controls but doesn't lock the blade. This saw is me to me so am I missing a step. I also tried locking the blade against a piece if wood but it was almost like the arbor would spin but blade stayed still. Ran the saw after and no issues of blade slipping or weird noises.