What is the test for providing a jury with a full and complete set of instructions in a personal injury case?

The legal principles are plain. Under section 1138, when the jury "desire to be informed on any point of law arising in the case, . . . the information required must be given . . . ." People v. Beardslee (1991) 53 Cal.3d 68 tells us that the court "has a primary duty to help the jury understand the legal principles it is asked to apply," but "[t]his does not mean the court must always elaborate on the standard instructions. Where the original instructions are themselves full and complete, the court has discretion under section 1138 to determine what additional explanations are sufficient to satisfy the jury's request for information." (Id. at p. 97.)