Up to you if you think it's worth fixing ,I've been given at least 5 Rover Shredders with 5 hp Briggs motors and I repaired one and sold it for $200 ,the cost of the repair $10 ,the other 4 I threw out as they were blowing smoke .
Sometime you can pickup an old 5 hp Rover mower for $50 with a good motor that you could swap into the shredder.
As far a I know the different length spring (short spring) is from the hot side of the motor being the exhaust spring ,the constant heat and age of the spring causes the spring to loose tension thus ending up with one shorter spring but I'm not a Briggs and Stratton mechanic so may need someone else's opinion here.
