Jumping from a conveyor belt with added velocity

I'm not sure if its the way my collisions or velocity functions are interacting, but the only thing that happens when I jump from this conveyor belt is a stunted little hop, barely off the ground. If I mash the keyboard, I might get a jump off here and there.

If it's the collisions, how might I set up a workaround to get off the ground?

If it's the velocity changes overwriting each other, how might I write them to get the constant motion that I need without interrupting the jump motion?

Thanks for your support

Excerpt from Character Motor Script

 function FixedUpdate(){
 
     if (DownwardG){
     rigidbody.AddForce(-gravity*rigidbody.mass*Vector3.up);
     }

     if (!ZeroGrav){
         if (!DownwardG){
     // apply constant weight force according to character normal:
     rigidbody.AddForce(-gravity*rigidbody.mass*myNormal);
     }  
     }
 
     
 
        if (Input.GetButtonDown("Jump")){ // jump pressed:
         if (isGrounded){ // no: if grounded, jump up
             //rigidbody.velocity += jumpSpeed * myNormal;
             rigidbody.velocity = jumpSpeed * myNormal;
             // rigidbody.velocity = Vector3(0,0,0);
             print("Jump!");
             //rigidbody.AddForce((550+gravity*rigidbody.mass)*myNormal);
 
         }                
 
     }

Conveyer belt script

 var x : float;
 
 var y : float;
 
 var z: float;
 
 //private var JumpFix : boolean = false;
 
 //private var OriginalVelocity : Vector3;
 
 private var MoveIt : boolean = false;
 
 private var ObjectToMove: GameObject;
 
  
 
  
 
 function FixedUpdate(){
 

 if (MoveIt){
 
 ObjectToMove.rigidbody.velocity = Vector3(x,y,z);

 //I thought something like this might help but it didn't, at least in the way I attempted
 
     //collidingObject.rigidbody.velocity = OriginalVelocity + Vector3(x,y,z);
 
     }
 
 }
 

 function OnCollisionStay(collidingObject : Collision)
 
 {
 
     print(x);
 
     print(y);
 
     print(z);
 
     ObjectToMove = collidingObject.gameObject;
 
     MoveIt = true;

 
 }
  
 
 function OnCollisionExit(collidingObject : Collision){
 
     print("exited");
 
     MoveIt = false;
 
     ObjectToMove.rigidbody.velocity = Vector3(0,0,0);
 
     }