The Toro website has a parts look up service. Perhaps with the exploded parts view you can figure out how to replace the spring. I haven't done that repair but it doesn't look too difficult.

I used the exploded diagram to identify the part needed, but it didn't really help in terms of how to take it apart. Sort of made it look like the main assembly just slides on & off, but there's definitely more to it than that. The puzzling thing is that I don't see any screws or fasteners to undo.

Easier than it looks. Just remove the handle entire handle from the bottom of the mower, (no need to remove your cables either) lay it on its side, and spread the handle apart and remove the bar and spring.

I need to replace the whole handle on my personal pace mower can’t find instructions anywhere I have a new handle