I believe it is time for a new set of blades. I always buy a extra set of blades, take off old set put on new, sharpen old put away. The secret to removing blades is to leave mower on tractor, raise up and put a jack stand next to the blade bolt between the bolt and gearbox under the T bar, lower on to jack stand. Remove the nut with a impact place a deep-well socket over the bolt like a sleeve (you need one that just fits) put a rod or square stock thru drive hole (1/2 for 1/2 drive or 3/4 for 3/4 drive) of socket. Take a 2x10 board that you have drilled so rod will pass thru it and place over rod and set down on top of deck.... take a BIG sledge and hit it hard, do not tap, the board will protect your deck if you miss. They will usually fall off on second hit.

I have been roadside mowing for a city for 20 years and recently have been clearing out some large 2 to 4 inch stuff and change blades quite often. Always use never-seize when reassembling.

Good luck
Jeff