was this servo operating the elevator or the boost tab, ??? If the boost tab, it is quite big for the job, as an insight, on my 35% Yak 54, I installed a small hitec 81 servo directly controlling the boost tab on the rudder. The rudder itself was free floating. On the ground for rudder/tail wheel operation, I would need a blip on the throttle to get some air but it worked beautifully.
In the air it worked very powerfully, did some very nice Knife Edge.

There was one problem though, since the Rudder also had an aerodynamic balance on the top of the rudder, in straight flight it would tend to oscillate. What I needed to do was install dampers on the rudder itself..

A properly installed boost tab on a control surface, using only a 25 oz servo controlling the boost tab, gives the control surface as much as 5000 oz of torque.

So, it would be nice to see how every thing was installed....

Roger