I purchased a PanaVise model 201 Jr. The maximum jaw opening was too small for my first project. The max Jaw opening is 2-7/8". This makes it mostly useless for most electronic work I want to do. So I replaced the screw and parallel sliders with longer pieces.
Stock photo from vendor.
The manufacture used .25 inch round bar. I had some O1 drill rod. The screw is 10-24, and I happened to have this stocked threaded rod.
The hard part was removing the T-knob from the threaded screw of the unmodified vise. I twisted it to where the threaded screw failed where there is a snap ring groove. Then I found the plastic knob has a brass insert in the plastic housing. It clearly was glued in with thread lock. I used a small torch to heat the screw up and then I could spin it out with pliers.
Machining a new snap ring groove was easy using a thin cutoff blade in the lathe. A bigger problem was the snap ring fell to the floor where I have a rubber mat with large holes and machining swarf. I found it after much looking. That is the one piece I found I don't have spare parts stocked, it was 1/8". My assortment, does not get below 1/4".
The vise now has a 9" clamping range.