I totally agree, it would be better to go to something more powerful. I believe the 9253 was meant only to be used with the Futaba Gyros as well... that could explain the oscillating without the gyro. Here's what Tower says:

"Designed exclusively as a tail rotor servo for F3C, 30, 46 and 60 sized helicopters, particularly with SMM gyros such as GY401, GY502."

On my 1/4 scale aerobat (Extra) I've used the Hitec 5945 digital (150 oz in @ .16 sec @ 4.8v) The 5925 does it at .08 sec @ 6v, pretty darn close the 9253 but with 100 more oz-in. of torque!