This isn’t really fixing anything but just minor tinkering. Still, it has worked so well I’ll mention it.
If you have a long hair cat or certain dog breeds, it needs brushing to remove excess undercoat and mats. The most effective tool is a detangling brush like Freshly Bailey Dog and Cat Dematting Tools - “Miracle” Undercoat Rake/Comb - Safe Dog Detangler and Cat Brush for Matted Hair/Fur - Easiest Pet Grooming Brush to Maintain Pet's Coat
https://www.amazon.com/dp/B07SR5M71B/ref=cm_sw_r_cp_api_glt_fabc_7DS13SJ2TQENXPE2M9EW
That tool can be improved by disassembling the blades and sharpening the small inner curved part of each blade. The edges come vaguely sharp or maybe just corner-ish, but it’s not really an edge. If you use a Dremel to put a real edge on the blades, the brush will remove 2x the undercoat with 1/2x the tugging at your pet’s skin.
I don’t think you want too keen an edge. You want the blades to comb through untangled fur, and only cut the fur when the edge encounters higher resistance like tangled undercoat or a mat of fur.