You might want to have that checked out...my 3rd SCV is silky smooth..could be a busted cable, kinked cable, etc... all it takes is one good kink when installing it and it will forever be tough to operate. I personally installed & adjusted mine and it works great....(Did you know there is a float Detent on the SCV...I've seen many machines come with the detent not functional because of improper adjustment)
The cables arent a "Cheap & Easy" solution on the cab models, I'd argue mechanical linkage is way cheaper & easier. The reason for cable controls is to completely isolate the levers & such from any vibration...mechanical linkage would introduce vibration on the lever which in turn would make the cab that much more noisy. JD has the quietest cab by far because of this.....