Have you tried going here
https://www.cubcadet.com/en_US/service-and-parts/service-parts.html AND searching using you full model number ?
Many newer models are just different bodies on older chassis so for most work you will fine the LTX manuals from here
https://www.cubcadetpartsnmore.com/cub-cadet-service-manuals will get you out of trouble.
The sneaky way is to use a web archive search engine that can find URL's that are no longer active but the files are still there , Wayback machine is reasonably good and search for the old web page
http://cubcadet.custhelp.com/app/answers/detail/a_id/1722/~/cub-cadet-professional-shop-manuals.
If the server that hosted it is still on line it can be recovered