So... you purchased an A128Pro or A129ProC a few years ago, it's still retracting strongly, but you managed to wear out the Flexible Adapter?  Not surprising! The guts (case, spring, string) of the PencilPull Pro are amazingly durable.  The Adapter is the  made from the best material we could muster - but it's like the tire of a car: it will wear out and eventually break down. 
Get this Adapter Replacement Set and your Pro will run like new!