I have same issue with a brand new Hitec 5996TG I am using on Mugen MBX6 throttle. I can't seem to find a rubber band that is powerful enough to pull it back to neutral in the event of lost power. The previous servo I had worked flawless, just lacked speed. I double checked all linkages, etc. Did I get a bad servo? This model is no longer made by Hitec but LHS had a bunch of them on sale.