Echo 15660140630. Amazon has one for $128. Yawzer! You could search ebay trimmer coil for one that is physically correct but would timing be correct? Dunno.
I've revived old, expensive, NLA coils with 2 hours in a toaster oven at 200*.
Most independent repair workshops will have piles of old trimers that were uneconomic to repair.
Most are there because the idiot owners ran them on strait fuel ( always blame their son or neighbour ).
However people who pay good money for top shelf products usually have sufficient intelligence & respect for their tools to make sure they always use premix.
However you might be lucky.
Down here franchised dealers can loose their franchise if they fit used parts and many of the franchise chains pay ( credit really ) the dealers to destroy all old equipment that does not get repaired because they want to force customers to buy new.
So ferret around repair only workshops but you can still expect to pay around 1/2 the new price.
Have you tested the coil by trying to run it without the kill wires connected ?
Are you sure it is not the plug cap ?