Advice on replacement throttle??

If you don't know why the previous one stuck then just replacing it might not help.

The entire throttle tube slides over the handlebars. The position of the tube is established by the portion that clamps to the handlebars. If you slide the tube on too far then the closed end of the throttle tube can contact the end of the bar and jam it. It may have been fine when first installed but crash (even a simple drop) can cause the entire throttle tube to get pushed father onto the bars to the point you have a problem.

If you install hand guards then you need to cut the end of the throttle tube out so the guards can mount to the bars. With the end cut out you can slide the tube a little farther on, which you need to do to ensure that the tube and grip doesn't contact the hand guards. After a fall the hand guards can get bent and what used to be OK may no longer be.

I doubt that the throttle twist grip mechanism is bad but it might need a little maintenance. Take it all apart and lubricate the moving parts. Lubricate the throttle cable(s). Make sure that the throttle tube has plenty of clearance to the end of the bars and hand guards. Make sure that the throttle tube isn't cracked.

Rod

Domino also makes some nice options.