How many extra links can you SAFELY remove?
This is a quickie method to determine how much extra chain you have. No sense getting your hands dirty if you don't need to.
Put it in BIG:BIG Cog/chainring.
You want 1-2" excess. More than that can exacerbate your problem to some degree, depending on "how much"
Does the RDER have adequate chain wrap & cog size capacity.
IOW, what's different then before?