JVC GY HD251:
Stick your camera in HD24p and let it re-boot
Press User 3 and Focus assist together then at the same time press and hold the status button for longer than a second. (so you are pressing 3 buttons at the same time here).
This will enter the relevant service menu and from here you will see Pixel Comp in the list. Scroll down and hit execute. The camera will (should) repair all of the dead pixels within about 15 seconds then ask you to power the camera off then on again.
JVC GY HM700:
.WARM CAMERA FOR 30 MINUTES
.SET CAMERA TO 720 60P
.POWER-UP PLUS PUSH THE DISPLAY BUTTON AT THE SAME TIME WHILE CAMERA IS POWERING.
.PRESS….MENU PLUS FOCUS ASSIST BUTTON AT THE SAME TIME
.ADVANCE MENU WILL APPEAR
.SCROLL TO ADVANCE FUNCTION
.PUSH: SET BUTTON
.SCROLL TO THE WORD: PIXEL COMPENDET
.PUSH: SET TO EXECUTE
.NOW: PHYSICALLY EXECUTE THE PROCESS
.EXECUTING WILL FLASH THEN STOP
NO MORE DEAD PIXEL(S)