What is wrond with your old one? Did it stretch out, if it did I made made a bracket that anyone with a drill press, some allen bolts, and washers also a piece of 1/16" thick 5"long x 3" wide can make. Their is a link below.
It seems to work fine when I take the cable out and move it back and forth. Also the throttle lever works fine, but when I put it all together, it is not smooth moving and takes a little force. Maybe a bit rusted in the cable?
You can lube cables by holding by one end running a few drops of oil down into them.
If it works smoothly off the bike though it might be something else like, routing, in the
lever itself, at the carb connection. Does the lever and butterfly on the carb work smoothly
with no cable?