If you're using the Norelco, snap the head off. Slide each cutter out of the plastic triangle. Then disassemble the comb and cutter. Brush out each piece. (I had long hair strands wound around stuff in there.) Water helps. Pick the hair out with a tweezer, and brush the heads and screens clean with hand wash soap and old tooth brush.
Then reassemble the combs and cutters, slide them back into the triangle, and snap back onto the razor. A tiny drop of oil on each comb and cutter might help, too. Silicone spray is better yet.
Shaves nicely, again. Easier and cheaper than going to buy a new shaver. No trip to the store needed.