HI i am in the process of installing mechanical retracts on a 40 size GP P-51,using Hitech HS-75 BB servo, spec wise they are the same as Futaba 136s but cost considerably less, has anyone used these,are these reliable servos?

I am having a hard time getting the travel distance right for the up/down positions, plus due to the arc of the servo arm i can this hear binding noise each the connecting rod travels, are there any special connectors that help, please let me know any help ful tips that you have...

Thanks


salman