I have the same problem with several strings.
These were purchased at Canadian tire, Noma will replace these strings free of charge up to five years.
You can separate these strings, they are basically 25 light strings joined together.
As Canadian tire does not have inventory at this time of year, they have given me a Purchase card to use when they bring in their fall inventory.
I think separating the string mighty be a waste of time because who knows how long they will continue to work.
I am going to replace them all with 25 light strings so they can be replaced or checked more easily!
Hope this helps!