So, you purchased a 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. 
Purchase this Adapter Kit and the Pro will run like new.