There was a post made about a guy who fixed that issue with Spline Shaft Repair:
(Pictures no longer on host site)
Or you can buy a new input shaft kit from Polaris but since your model is e580 (48v system w/ 2.6hp motor) I’m not sure if you differential gear ratio is 8.9:1 or 10.35:1. If its 8.9:1 they don’t have it.
10.35:1 Polaris PN: 2878944
Also replace the resilient bumper that’s inside the female end of the motor. Polaris PN: 5414407
Someone might know where you can buy this from a 3rd party source, I would like to know.