You have to remove both the pin through the driveshaft coupling (part #5} and the coupling arm (part #2) then slide the whole works forward enough to raise the shaft along with the flex disc joint and fan for removal.
Some cleaning of rust, scale and paint may be required to slide these parts forward, shop emery cloth is good for this.
Then reassemble in the reverse order
This would also be a good time to inspect the front rag joint along with the driver and bushing on the rear of the engine as well for wear and/or deterioration of the flex disc joint. Easy enough to remove once the rear parts are loosened up and slid forward.
See link attached, upper right hand corner.
https://www.cubcadet.com/en_US/ari-p...3cb861d601fd/y