Have you considered an electric mower? Cub Cadet makes an electric xt1 and a electric version of the cc30. Ryobi makes an electric ride on mower and zero turn. Before I bought my 3000 series tractors I considered the Ryobi ride on. I really wanted to use for snow removal and that does not have a snow blower. No changing oil, no gasoline to haul. Just plug it in.
If you can repair your current lawn tractor mostly your self, that will probably be the cheapest. If you need to pay a shop to get it repaired, then buying a different one and selling what you have may be a better deal.
I personally would really consider an electric tractor, but it needs a good snow blower. And those are not available yet.
https://www.cubcadet.com/en_US/ridin...-riding-mowers
https://www.homedepot.com/p/RYOBI-38...8111/300422546