Finish mower problem

[JDL538]

I have a Kioti 72 in. finish mower. The right blade has dropped down about 3/4 of an inch. I can pull it back up by the pulley but it drops down again when I run it. It cuts fine just wondering what is causing this. Any ideas?

 

[DJ54]

If your deck is similar to this one, could be the bearing hub flange bolts loosened, or, the flange itself has been eaten away from the acid in the grass, and allowed it to drop. The bearing hubs on my '88 Wheel Horses are made of aluminum, and eaten away by the acid in the grass.

https://www.tractorpartscentral.com/catalog/FM2.jpg