I have a GY401 and Futaba 9253 on the tail, I cannot get the servo to stop singing when I connect the servo horn, have tried five different servo horns, realigning the push rod, everything I can think of, it will stop singing without the servo horn and rod attached, once I put it on and move the stick it sings..... there is some play in the shaft of the servo, about 2 mm up and down when the servo is placed facing flat down. Is this normal, is the servo bad or the alignment: Am using this on a Venture 30 with JR 8103 digital, confused: Thanks for any help.......

What melody does it sing?

If you mean a hmmm noise than the digital servo should do that. Also make sure the servo is not binding.

Yes digital servos "sing". Unlike there analog (standard) counterparts. AS far as the play you are experiencing, 2mm worth of play is excessive. Understand that the play in your servo for your tail rotor control should not be no more than your other servos. Tail rotor servos are built for high speed and the gear ratio for reduction from the motor may "appear" sloppier than with other servos when in fact they are not.