2013 Simplicity Prestige (2690953) mower blades slow in reverse?!

[Catenary Kid]

About two years ago, my Simplicity mower blades started noticeably slowing down when I reverse it, which I do frequently. It works fine when going forward, but when I step on the reverse pedal, I can hear the blades slowing down considerably. It still mows, but not as well. I changed the drive pulley in '20 and the deck drive belt in '22 and the main drive belt this year, no change. The engine maintains RPM's just fine, but the plades slow. Any suggestions?

 

[StarTech]

Sounds like you got quite a bit in the deck linkages along a worn engine to deck belt. Also check the moveable spring loaded idlers for binding.