Unsurprising, especially if you're not the original owner.
Admittedly, the gun has been "inspected", exploring the "problem" quite a bit outside the company's hands.
This is starting to look like a major issue is probably involved, and their engineers are familiar enough with their products to be able to have an idea of whether or not they ought to look at it for being a suspected design/materials defect.
Guns wear out at some point. Or may experience ammunition issues that can create accelerated wear & tear, or even damage, not envisioned or considered normal by the factory. How often has the recoil spring been replaced, anyway? If you're not the original owner, how can you know how the gun was treated and maintained by the previous owner(s)?
The all-steel 4006's were(are) robust guns, but I've learned of a small number of older, well-used 4006's that eventually experienced cracks in barrels, slides or frames after enough rounds had been fired through them. Also, the company hasn't been making replacement barrels or slides for the older standard 3rd gen 4006's for some years (and TSW barrels don't fit the older slides, and the TSW slides don't fit the older frames).
FWIW, have you thought about trying to call Frank in TX (authorized warranty center)? Maybe he might have a different perspective than the "front line" customer service representative with whom you were probably exchanging emails. Can't hurt to try. If he isn't interested in inspecting the aging gun under "warranty", maybe he might have a different suggestion to consider.
Worth a call, maybe. I've never had occasion to use his services. (I'm an armorer, and when an occasional problem might come along beyond the scope of an armorer level field repair, I shipped them to the factory.) I've read good things about him and his shop by forum members, though.
LSG
10059 HWY 1476
COMANCHE, TX 76442
Phone: (325) 885-2700
Email:
[email protected] Web:
LSG, Mfg|Gun Parts|Warranty|Gunsmithing
Just some thoughts.
Thank you for sharing it with us. 
