I have some old RC cars and electronics from about 25 years ago that I am trying to get to work for my kids. When I first reconnected everything (with a new battery), everything worked fine.

I went move the electronics to another car and overtightened the servo screw and messed it up so it would take stop twitching.

I bought a new in box futaba servo, same as before fp-s148 and now it works again, but I am running into issues with the steering responding when using the throttle. It will be moving and when. I turn the wheel on the transmitter, the stetheng won't turn right away, it's not responsive. I tried this on two different cars and same thing, one with a steering mechanism and one with just straight tie rod connections.

I tried elevating the car to be able to hit the throttle and see the steering up close and it seems better, just when it's away. I even tried moving back and it was fine, so seems like only when on the ground and moving.

Not sure what's up, they are old vintage electronics but worked before I had to replace the service.

Anything else I can try to troubleshoot?