Originally Posted by
John E
You do not need to replace your freewheel before replacing your chain. It is more important to replace your chain whenever it has elongated more than 0.5 percent, to avoid accelerated wear on the chainrings and freewheel cogs.
Pastor Bob in NH in our C&V forums is the resident freewheel restoration expert.
The chain is already more than 0.75 percent out so it has probably done some damage, it has not been changed since 1990.