Not surprising that parts are no longer available. These curve shafts here are considered disposable units. They are sold a lot of the time below many repair shops minimum labor rates. Even with me @ 45 usd / hr. Spending over an hour making repairs plus parts it quickly exceed replacement. There is a lot of the time I way under charge for my time just to help a senior citizen out. Even then repairs are expensive.
Yes it is possible the recoil spring from another brand may work as Husqvarna didn't make the unit just rebranded it. Now if you got several junkers as I do around here you can try matching up the recoil spring from one of them. But you see even most other OEMs are going to assemblies instead of individual parts.
Just a shame that some repairable equipment dies because a lack of parts but this is intentional by OEMs to force the end user into replacing equipment.
