There are currently two of these presses on E-bay. The older one has an s.n. in the 21XX range, with the newer in the 45XX range. The older model shows a shell holder "arm" which apparently uses one or two set screws to retain the shell holder while the newer model has an apparently modified "arm" which uses a slotted steel plate with socket head capscrews in addition to the aforementioned set screws to retain the shell holder. Is this a factory modification or is there a design problem which someone attempted to address?