Help! Servos making weird rumbling noise

[Harry Joelsson]

https://imgur.com/a/wt5ovKM

Using Power Pack B and the 9G servos.

 

[LitterBug]

They sound like typical servos, potentially under a bit of a bind. Make sure the control surfaces and push rods move freely in the range of travel they are supposed to travel. Test each surface one by one to help determine if it is a particular surface or servo that needs attention.

LB

 

[CrshNBrn]

That's a nice black finish you've got there. But yes, Litterbug is right. Checking one rod and surface at a time for free movement is the way to problem solve this one.

 

[quorneng]

To convince yourself the servo is actually fine just slacken off the rod retaining screw so the rod does not move with the servo. I bet the servo will sound perfectly alright indicating that the linkage is too stiff and over loading the servo.
In a full size light plane if no one is holding the stick the elevator will "flop" to its bottom stop just under it own weight! That is how free moving the hinges and linkage are.
Virtually impossible to achieve in a small model but it should be the target for all control set ups. You cannot afford to waste the power of a servo. Save it for moving the control surface against the moving air.