Do you need just the spring, or the whole assembly including the gear and sleeve?
If you need just the spring, can’t you find one of equal length, wire size & tension in a industrial parts supply company like McMaster-Carr.com?
I did my timing chain last year and I am not sure the spring in the tensioner is anything special, per se.
I have an extra assembly and I think the spring is good, but I have to look to see how hard it is to get out of the assembly.
Please advise as to your thoughts on the matter.