I bought one of Thompson Centers rifles at an auction sale and the sear wouldnt engage the tumbler unless the weapon was held barrel down.I inspected the lock and discovered the spring that held tension on the tumbler was frozen because of improper maintence of the lock.I telephoned Thompson and spoke to a nice lady who told me that the rifle I had was a very eairly production of that model and because of that fact it was necessary to inspect some old parts manuals.I told her that if the part was available I would like to purchase the same.A few days later I received the part in the mail free of charge.You just don't get any better than that!